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Alonso SDV, González Flecha FL. Fifty years of biophysics in Argentina. Biophys Rev 2023; 15:431-438. [PMID: 37681102 PMCID: PMC10480372 DOI: 10.1007/s12551-023-01114-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Accepted: 08/10/2023] [Indexed: 09/09/2023] Open
Abstract
In 1972, a group of young Argentinean scientists nucleated in the so-called Membrane Club constituted the Biophysical Society of Argentina (SAB). Over the years, this Society has grown and embraced new areas of research and emerging technologies. In this commentary, we provide an overview of the early stages of biophysics development in Argentina and highlight some of the notable achievements made during the past five decades. The SAB Annual Meetings have been a platform for intense scientific discussions, and the Society has fostered numerous international connections, becoming a hallmark of SAB activities over these 50 years. Initially centered on membrane biophysics, SAB focus has since expanded to encompass diverse fields such as molecular, cellular, and systems biophysics.
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Affiliation(s)
- Silvia del V. Alonso
- Laboratorio de Bio-Nanotecnología, Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Bernal, Argentina
- Grupo de Biología Estructural y Biotecnología (GBEyB), IMBICE (CONICET CCT-La Plata), La Plata, Argentina
| | - F. Luis González Flecha
- Laboratorio de Biofísica Molecular, Instituto de Química y Fisicoquímica Biológicas, Universidad de Buenos Aires – CONICET, Buenos Aires, Argentina
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2
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Sims JN, Yun EJ, Chu J, Siddiqui MA, Desai SA. A robust fluorescence-based assay for human erythrocyte Ca ++ efflux suitable for high-throughput inhibitor screens. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2023; 52:101-110. [PMID: 36512028 PMCID: PMC11019861 DOI: 10.1007/s00249-022-01623-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Revised: 10/20/2022] [Accepted: 11/27/2022] [Indexed: 12/14/2022]
Abstract
Intracellular calcium is maintained at very low concentrations through the action of PMCA Ca++ extrusion pumps. Although much of our knowledge about these Ca++ extrusion pumps derives from studies with human erythrocytes, kinetic studies of Ca++ transport for these cells are limited to radioisotope flux measurements. Here, we developed a robust, microplate-based assay for erythrocyte Ca++ efflux using extracellular fluorescent Ca++ indicators. We optimized Ca++ loading with the A23187 ionophore, established conditions for removal of the ionophore, and adjusted fluorescent dye sensitivity by addition of extracellular EGTA to allow continuous tracking of Ca++ efflux. Efflux kinetics were accelerated by glucose and inhibited in a dose-dependent manner by the nonspecific inhibitor vanadate, revealing that Ca++ pump activity can be tracked in a 384-well microplate format. These studies enable radioisotope-free kinetic measurements of the Ca++ pump and should facilitate screens for specific inhibitors of this essential transport activity.
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Affiliation(s)
- Jeremiah N Sims
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
- Institute of Protein Design, Medical Scientist Training Program, Molecular and Cellular Biology Program, University of Washington, Seattle, WA, USA
| | - EJun Yun
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
- Department of Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Jonathan Chu
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Mansoor A Siddiqui
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA
| | - Sanjay A Desai
- Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Rockville, MD, USA.
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3
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Saffioti NA, de Sautu M, Ferreira-Gomes MS, Rossi RC, Berlin J, Rossi JPFC, Mangialavori IC. E2P-like states of plasma membrane Ca 2+‑ATPase characterization of vanadate and fluoride-stabilized phosphoenzyme analogues. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1861:366-379. [PMID: 30419189 DOI: 10.1016/j.bbamem.2018.11.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Revised: 10/22/2018] [Accepted: 11/01/2018] [Indexed: 01/18/2023]
Abstract
The plasma membrane Ca2+‑ATPase (PMCA) belongs to the family of P-type ATPases, which share the formation of an acid-stable phosphorylated intermediate as part of their reaction cycle. The crystal structure of PMCA is currently lacking. Its abundance is approximately 0.1% of the total protein in the membrane, hampering efforts to produce suitable crystals for X-ray structure analysis. In this work we characterized the effect of beryllium fluoride (BeFx), aluminium fluoride (AlFx) and magnesium fluoride (MgFx) on PMCA. These compounds are known inhibitors of P-type ATPases that stabilize E2P ground, E2·P phosphoryl transition and E2·Pi product states. Our results show that the phosphate analogues BeFx, AlFx and MgFx inhibit PMCA Ca2+‑ATPase activity, phosphatase activity and phosphorylation with high apparent affinity. Ca2+‑ATPase inhibition by AlFx and BeFx depended on Mg2+ concentration indicating that this ion stabilizes the complex between these inhibitors and the enzyme. Low pH increases AlFx and BeFx but not MgFx apparent affinity. Eosin fluorescent probe binds with high affinity to the nucleotide binding site of PMCA. The fluorescence of eosin decreases when fluoride complexes bind to PMCA indicating that the environment of the nucleotide binding site is less hydrophobic in E2P-like states. Finally, measuring the time course of E → E2P-like conformational change, we proposed a kinetic model for the binding of fluoride complexes and vanadate to PMCA. In summary, our results show that these fluoride complexes reveal different states of phosphorylated intermediates belonging to the mechanism of hydrolysis of ATP by the PMCA.
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Affiliation(s)
- Nicolás A Saffioti
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Facultad de Farmacia y Bioquímica, Junín 956, Ciudad Autónoma de Buenos Aires C1113AAD, Argentina
| | - Marilina de Sautu
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Facultad de Farmacia y Bioquímica, Junín 956, Ciudad Autónoma de Buenos Aires C1113AAD, Argentina
| | - Mariela S Ferreira-Gomes
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Facultad de Farmacia y Bioquímica, Junín 956, Ciudad Autónoma de Buenos Aires C1113AAD, Argentina
| | - Rolando C Rossi
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Facultad de Farmacia y Bioquímica, Junín 956, Ciudad Autónoma de Buenos Aires C1113AAD, Argentina
| | - Joshua Berlin
- Department of Pharmacology and Physiology, New Jersey Medical School, Rutgers University, Newark, NJ, USA
| | - Juan Pablo F C Rossi
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Facultad de Farmacia y Bioquímica, Junín 956, Ciudad Autónoma de Buenos Aires C1113AAD, Argentina
| | - Irene C Mangialavori
- Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Instituto de Química y Fisicoquímica Biológicas (IQUIFIB), Facultad de Farmacia y Bioquímica, Junín 956, Ciudad Autónoma de Buenos Aires C1113AAD, Argentina.
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4
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Evaluation of lipid peroxidation and the level of some elements in rat erythrocytes during separate and combined vanadium and magnesium administration. Chem Biol Interact 2018; 293:1-10. [PMID: 30028963 DOI: 10.1016/j.cbi.2018.07.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 07/02/2018] [Accepted: 07/16/2018] [Indexed: 12/18/2022]
Abstract
The impact of vanadium (V) and magnesium (Mg) as sodium metavanadate (SMV, 0.125 mg V/ml) and magnesium sulfate (MS, 0.06 mg Mg/ml) on lipid peroxidation (LPO) and selected elements in the rat erythrocytes (RBCs) was investigated. Relationships between some indices determined in RBC were also studied. SMV alone (Group II) elevated the malondialdehyde level (MDARBC) (by 95% and 60%), compared with the control (Group I) and MS-supplemented rats (Group III), respectively, reduced the concentration of CuRBC (by 23.5%), in comparison with Group I, but did not change the levels of NaRBC, KRBC, and CaRBC, whereas MS alone (Group III) only reduced the CuRBC concentration (by 22%), compared with Group I. The SMV + MS combination (Group IV) reduced and elevated the CuRBC (by 24%) and CaRBC (by 111%) concentrations, respectively, in comparison with Groups I and III, and these changes were induced by the V-Mg antagonistic and synergistic interaction, respectively. The combined SMV + MS effect also enhanced the MDARBC level, compared with Groups I (by 79%) and III (by 47%) and slightly limited its concentration, compared with Group II, which, in turn, resulted from the distinct trend toward the V-Mg antagonistic interaction. We can conclude that V (as SMV) is able to stimulate LPO in rat RBCs and that V-Mg interactive effects are involved in changes in CuRBC, CaRBC, and MDARBC. Further studies are needed to elucidate the exact mechanisms of the V-Mg antagonistic/synergistic interactions and to provide insight into the biochemical mechanisms of changes in rats suffering from anemia [1], characterized by a disrupted antioxidant barrier in RBCs [2] and an intensified free radical process in these cells.
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Aluminum inhibits the plasma membrane and sarcoplasmic reticulum Ca 2+-ATPases by different mechanisms. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:1580-1588. [PMID: 29859139 DOI: 10.1016/j.bbamem.2018.05.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/25/2018] [Revised: 04/28/2018] [Accepted: 05/25/2018] [Indexed: 11/21/2022]
Abstract
Aluminum (Al3+) is involved in the pathophysiology of neurodegenerative disorders. The mechanisms that have been proposed to explain the action of Al3+ toxicity are linked to changes in the cellular calcium homeostasis, placing the transporting calcium pumps as potential targets. The aim of this work was to study the molecular inhibitory mechanism of Al3+ on Ca2+-ATPases such as the plasma membrane and the sarcoplasmic reticulum calcium pumps (PMCA and SERCA, respectively). These P-ATPases transport Ca2+ actively from the cytoplasm towards the extracellular medium and to the sarcoplasmic reticulum, respectively. For this purpose, we performed enzymatic measurements of the effect of Al3+ on purified preparations of PMCA and SERCA. Our results show that Al3+ is an irreversible inhibitor of PMCA and a slowly-reversible inhibitor of SERCA. The binding of Al3+ is affected by Ca2+ in SERCA, though not in PMCA. Al3+ prevents the phosphorylation of SERCA and, conversely, the dephosphorylation of PMCA. The dephosphorylation time courses of the complex formed by PMCA and Al3+ (EPAl) in the presence of ADP or ATP show that EPAl is composed mainly by the conformer E2P. This work shows for the first time a distinct mechanism of Al3+ inhibition that involves different intermediates of the reaction cycle of these two Ca2+-ATPases.
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6
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Mangialavori IC, Ferreira-Gomes MS, Saffioti NA, González-Lebrero RM, Rossi RC, Rossi JPFC. Conformational changes produced by ATP binding to the plasma membrane calcium pump. J Biol Chem 2013; 288:31030-41. [PMID: 24025327 DOI: 10.1074/jbc.m113.494633] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The aim of this work was to study the plasma membrane calcium pump (PMCA) reaction cycle by characterizing conformational changes associated with calcium, ATP, and vanadate binding to purified PMCA. This was accomplished by studying the exposure of PMCA to surrounding phospholipids by measuring the incorporation of the photoactivatable phosphatidylcholine analog 1-O-hexadecanoyl-2-O-[9-[[[2-[(125)I]iodo-4-(trifluoromethyl-3H-diazirin-3-yl)benzyl]oxy]carbonyl]nonanoyl]-sn-glycero-3-phosphocholine to the protein. ATP could bind to the different vanadate-bound states of the enzyme either in the presence or in the absence of Ca(2+) with high apparent affinity. Conformational movements of the ATP binding domain were determined using the fluorescent analog 2'(3')-O-(2,4,6-trinitrophenyl)adenosine 5'-triphosphate. To assess the conformational behavior of the Ca(2+) binding domain, we also studied the occlusion of Ca(2+), both in the presence and in the absence of ATP and with or without vanadate. Results show the existence of occluded species in the presence of vanadate and/or ATP. This allowed the development of a model that describes the transport of Ca(2+) and its relation with ATP hydrolysis. This is the first approach that uses a conformational study to describe the PMCA P-type ATPase reaction cycle, adding important features to the classical E1-E2 model devised using kinetics methodology only.
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Affiliation(s)
- Irene C Mangialavori
- From the Instituto de Química y Fisicoquímica Biologicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Consejo Nacional de Investigaciones Científicas y Técnicas, Junín 956 (1113) Buenos Aires, Argentina
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7
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Mangialavori IC, Caride AJ, Rossi RC, Rossi JPFC, Strehler EE. Diving Into the Lipid Bilayer to Investigate the Transmembrane Organization and Conformational State Transitions of P-type Ion ATPases. ACTA ACUST UNITED AC 2011; 5:118-129. [PMID: 21691422 DOI: 10.2174/187231311795243319] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although membrane proteins constitute more than 20% of the total proteins, the structures of only a few are known in detail. An important group of integral membrane proteins are ion-transporting ATPases of the P-type family, which share the formation of an acid-stable phosphorylated intermediate as part of their reaction cycle. There are several crystal structures of the sarcoplasmic reticulum Ca(2+) pump (SERCA) revealing different conformations, and recently, crystal structures of the H(+)-ATPase and the Na(+)/K(+)-ATPase were reported as well. However, there are no atomic resolution structures for other P-type ATPases including the plasma membrane calcium pump (PMCA), which is integral to cellular Ca(2+) signaling. Crystallization of these proteins is challenging because there is often no natural source from which the protein can be obtained in large quantities, and the presence of multiple isoforms in the same tissue further complicates efforts to obtain homogeneous samples suitable for crystallization. Alternative techniques to study structural aspects and conformational transitions in the PMCAs (and other P-type ATPases) have therefore been developed. Specifically, information about the structure and assembly of the transmembrane domain of an integral membrane protein can be obtained from an analysis of the lipid-protein interactions. Here, we review recent efforts using different hydrophobic photo-labeling methods to study the non-covalent interactions between the PMCA and surrounding phospholipids under different experimental conditions, and discuss how the use of these lipid probes can reveal valuable information on the membrane organization and conformational state transitions in the PMCA, Na(+)/K(+)-ATPase, and other P-type ATPases.
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Affiliation(s)
- Irene C Mangialavori
- Instituto de Química y Fisicoquímica Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, CONICET, Junín 956 (1113) Buenos Aires, Argentina
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8
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Vandorpe DH, Xu C, Shmukler BE, Otterbein LE, Trudel M, Sachs F, Gottlieb PA, Brugnara C, Alper SL. Hypoxia activates a Ca2+-permeable cation conductance sensitive to carbon monoxide and to GsMTx-4 in human and mouse sickle erythrocytes. PLoS One 2010; 5:e8732. [PMID: 20090940 PMCID: PMC2806905 DOI: 10.1371/journal.pone.0008732] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Accepted: 12/18/2009] [Indexed: 01/23/2023] Open
Abstract
Background Deoxygenation of sickle erythrocytes activates a cation permeability of unknown molecular identity (Psickle), leading to elevated intracellular [Ca2+] ([Ca2+]i) and subsequent activation of KCa 3.1. The resulting erythrocyte volume decrease elevates intracellular hemoglobin S (HbSS) concentration, accelerates deoxygenation-induced HbSS polymerization, and increases the likelihood of cell sickling. Deoxygenation-induced currents sharing some properties of Psickle have been recorded from sickle erythrocytes in whole cell configuration. Methodology/Principal Findings We now show by cell-attached and nystatin-permeabilized patch clamp recording from sickle erythrocytes of mouse and human that deoxygenation reversibly activates a Ca2+- and cation-permeable conductance sensitive to inhibition by Grammastola spatulata mechanotoxin-4 (GsMTx-4; 1 µM), dipyridamole (100 µM), DIDS (100 µM), and carbon monoxide (25 ppm pretreatment). Deoxygenation also elevates sickle erythrocyte [Ca2+]i, in a manner similarly inhibited by GsMTx-4 and by carbon monoxide. Normal human and mouse erythrocytes do not exhibit these responses to deoxygenation. Deoxygenation-induced elevation of [Ca2+]i in mouse sickle erythrocytes did not require KCa3.1 activity. Conclusions/Significance The electrophysiological and fluorimetric data provide compelling evidence in sickle erythrocytes of mouse and human for a deoxygenation-induced, reversible, Ca2+-permeable cation conductance blocked by inhibition of HbSS polymerization and by an inhibitor of strctch-activated cation channels. This cation permeability pathway is likely an important source of intracellular Ca2+ for pathologic activation of KCa3.1 in sickle erythrocytes. Blockade of this pathway represents a novel therapeutic approach for treatment of sickle disease.
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Affiliation(s)
- David H. Vandorpe
- Molecular and Vascular Medicine Unit, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Renal Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Chang Xu
- Molecular and Vascular Medicine Unit, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Renal Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Boris E. Shmukler
- Molecular and Vascular Medicine Unit, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Renal Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Leo E. Otterbein
- Department of Surgery, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Surgery, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Marie Trudel
- Institut de Recherches Cliniques de Montreal, Montreal, Quebec, Canada
| | - Frederick Sachs
- Department of Physiology and Biophysics, University of Buffalo, Buffalo, New York, United States of America
| | - Philip A. Gottlieb
- Department of Physiology and Biophysics, University of Buffalo, Buffalo, New York, United States of America
| | - Carlo Brugnara
- Department of Laboratory Medicine, Children's Hospital Boston Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Pathology, Harvard Medical School, Boston, Massachusetts, United States of America
| | - Seth L. Alper
- Molecular and Vascular Medicine Unit, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Renal Division, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts, United States of America
- Department of Medicine, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail:
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Mangialavori I, Villamil Giraldo AM, Marino Buslje C, Ferreira Gomes M, Caride AJ, Rossi JPFC. A new conformation in sarcoplasmic reticulum calcium pump and plasma membrane Ca2+ pumps revealed by a photoactivatable phospholipidic probe. J Biol Chem 2008; 284:4823-8. [PMID: 19074772 DOI: 10.1074/jbc.m806912200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The purpose of this work was to obtain structural information about conformational changes in the membrane region of the sarcoplasmic reticulum (SERCA) and plasma membrane (PMCA) Ca(2+) pumps. We have assessed changes in the overall exposure of these proteins to surrounding lipids by quantifying the extent of protein labeling by a photoactivatable phosphatidylcholine analog 1-palmitoyl-2-[9-[2'-[(125)I]iodo-4'-(trifluoromethyldiazirinyl)-benzyloxycarbonyl]-nonaoyl]-sn-glycero-3-phosphocholine ([(125)I]TID-PC/16) under different conditions. We determined the following. 1) Incorporation of [(125)I]TID-PC/16 to SERCA decreases 25% when labeling is performed in the presence of Ca(2+). This decrease in labeling matches qualitatively the decrease in transmembrane surface exposed to the solvent calculated from crystallographic data for SERCA structures. 2) Labeling of PMCA incubated with Ca(2+) and calmodulin decreases by approximately the same amount. However, incubation with Ca(2+) alone increases labeling by more than 50%. Addition of C28, a peptide that prevents activation of PMCA by calmodulin, yields similar results. C28 has also been shown to inhibit ATPase SERCA activity. Interestingly, incubation of SERCA with C28 also increases [(125)I]TID-PC/16 incorporation to the protein. These results suggest that in both proteins there are two different E(1) conformations as follows: one that is auto-inhibited and is in contact with a higher amount of lipids (Ca(2+) + C28 for SERCA and Ca(2+) alone for PMCA), and one in which the enzyme is fully active (Ca(2+) for SERCA and Ca(2+)-calmodulin for PMCA) and that exhibits a more compact transmembrane arrangement. These results are the first evidence that there is an autoinhibited conformation in these P-type ATPases, which involves both the cytoplasmic regions and the transmembrane segments.
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Affiliation(s)
- Irene Mangialavori
- Instituto de Química y Fisicoquímica Biológicas, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, CONICET, Junín 956 (1113) Buenos Aires, Argentina
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10
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Samanta S, Chatterjee M, Ghosh B, Rajkumar M, Rana A, Chatterjee M. Vanadium and 1, 25 (OH)2 vitamin D3 combination in inhibitions of 1,2, dimethylhydrazine-induced rat colon carcinogenesis. Biochim Biophys Acta Gen Subj 2008; 1780:1106-14. [DOI: 10.1016/j.bbagen.2008.05.003] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Revised: 04/29/2008] [Accepted: 05/05/2008] [Indexed: 11/28/2022]
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11
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Delgado-Coello B, Trejo R, Mas-Oliva J. Is there a specific role for the plasma membrane Ca2+ -ATPase in the hepatocyte? Mol Cell Biochem 2006; 285:1-15. [PMID: 16477375 DOI: 10.1007/s11010-005-9060-z] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2005] [Accepted: 10/18/2005] [Indexed: 10/25/2022]
Abstract
The plasma membrane Ca2+ -ATPase (PMCA) is responsible for the fine, long-term regulation of the cytoplasmic calcium concentration by extrusion of this cation from the cell. Although the general kinetic mechanisms for the action of both, well coordinated hydrolytic activity and calcium transport are reasonably understood in the majority of cell types, due to the complex physiologic and biochemical characteristics shown by the hepatocyte, the study of this enzyme in this cell type has become a real challenge. Here, we review the various molecular aspects known to date to be associated with liver PMCA activity, and outline the strategies to follow for establishing the role of this enzyme in the overall physiology of the hepatocyte. In this way, we first concentrate on the basic biochemical aspects of liver cell PMCA, and place an important emphasis on expression of its molecular forms to finally focus on the critical hormonal regulation of the enzyme. Although these complex aspects have been studied mainly under normal conditions, the significance of PMCA in the calcium homeostasis of an abnormal liver cell is also reviewed.
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Affiliation(s)
- Blanca Delgado-Coello
- Instituto de Fisiología Celular, Universidad Nacional Autónoma de México. México, México, D.F. México
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12
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Tiffert T, Lew VL. Kinetics of inhibition of the plasma membrane calcium pump by vanadate in intact human red cells. Cell Calcium 2001; 30:337-42. [PMID: 11733940 DOI: 10.1054/ceca.2001.0241] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The lack of specific inhibitors of the plasma membrane Ca2+ pump (PMCA) has made vanadate (VO3-), a non-specific inhibitor, an invaluable tool in the study of PMCA function. However, three important properties of vanadate as an inhibitor of the PMCA in intact cells, namely its speed of action in different experimental conditions, the reversibility of its inhibitory effects at different doses, and its dose-response, had never been characterized, despite extensive use. We report here the speed, reversibility and dose-response of PMCA inhibition by vanadate in intact human red cells. Near maximal inhibitory concentrations (1mM) in the red cell suspension blocked almost instantly the uphill Ca2+ extrusion by the PMCA, regardless of the intracellular Ca2+ concentration, cation composition of the external media, membrane potential or volume-stability of the cell. PMCA inhibition by vanadate, at concentrations of 10mM and 1mM, was not reversed by washing, resuspending, and incubating the cells for up to 2h in vanadate-free media. Vanadate inhibited PMCA-mediated Ca2+ efflux in intact red cells with a K1/2 of approximately 3 microM, a value similar to that described for the Ca2+-ATPase in isolated red cell membranes.
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Affiliation(s)
- T Tiffert
- Physiological Laboratory, University of Cambridge, Downing Street, Cambridge, UK.
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13
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Basak R, Basu M, Chatterjee M. Combined supplementation of vanadium and 1alpha,25-dihydroxyvitamin D(3) inhibit diethylnitrosamine-induced rat liver carcinogenesis. Chem Biol Interact 2000; 128:1-18. [PMID: 10996297 DOI: 10.1016/s0009-2797(00)00183-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A combination of a differentiation-inducing agent like 1alpha, 25-dihydroxyvitamin D(3) [1,25(OH)(2)D(3)] with a compound that blocks entry of calcium into cells like vanadium (V) may offer a new approach to differentiation therapy and address the problem of hypercalcemia. Initiation of hepatocarcinogenesis was performed by a single intraperitoneal injection of diethylnitrosamine (DEN) (200 mg/kg b.wt.) in male Sprague-Dawley rats. Supplementation of V, 1, 25(OH)(2)D(3), or both V and 1,25(OH)(2)D(3) were started 4 weeks prior to DEN injection and continued thereafter till 20th week. It was observed that supplementation of V (0.5 ppm) in drinking water ad libitum or 1,25(OH)(2)D(3) (3 microg/ml propylene glycol) per os twice weekly for the entire period of the experiment significantly reduces the number and size of hyperplastic nodules while the combination treatment offered an additive effect in reducing it to 37.5% from 83.3%. V-1,25(OH)(2)D(3) combination was also effective in elevating the level of hepatic microsomal cytochrome P-450 (Cyt. P-450) (P<0.001). Moreover, A significant reduced level of cytosolic glutathione (GSH) (P<0.001) and glutathione S-transferase (GST) (P<0.001) activity as well as reduction in the appearance of gamma-glutamyltranspeptidase (GGT)-positive foci (P<0.001) as compared to carcinogen control were observed in V plus 1, 25(OH)(2)D(3) treated group. These results suggest that V may be useful in combination with 1,25(OH)(2)D(3) in the inhibition of experimental rat hepatocarcinogenesis.
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Affiliation(s)
- R Basak
- Division of Biochemistry, Department of Pharmaceutical Technology, Jadavpur University, PO Box 17028, 700 032, Calcutta, India.
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14
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Abstract
Mitochondria are thought to be important in clearing calcium from synaptic terminals. It is unclear, however, whether the principal role of mitochondria in pre-synaptic calcium handling is to take up Ca2+ directly or to fuel Ca2+ removal by other mechanisms. We used patch clamp techniques and fluorescence imaging to examine calcium clearance mechanisms, including mitochondrial uptake, in single synaptic terminals of retinal bipolar neurons. We found that extrusion through the ATP-dependent Ca2+ pump of the plasma membrane is the dominant form of Ca2+ removal in the synaptic terminal. Calcium uptake into mitochondria was sometimes evident with large Ca2+ loads but was consistently observed only when plasma membrane extrusion was inhibited. We conclude that mitochondria act primarily as an energy source in clearance of Ca2+ from bipolar cell synaptic terminals.
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Affiliation(s)
- D Zenisek
- Department of Neurobiology and Behavior, State University of New York, Stony Brook 11794, USA
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15
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16
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Genazzani AA, Galione A. Nicotinic acid-adenine dinucleotide phosphate mobilizes Ca2+ from a thapsigargin-insensitive pool. Biochem J 1996; 315 ( Pt 3):721-5. [PMID: 8645149 PMCID: PMC1217266 DOI: 10.1042/bj3150721] [Citation(s) in RCA: 150] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Nicotinic acid-adenine dinucleotide phosphate (NAADP) is a novel intracellular Ca2+ releasing agent recently described in sea-urchin eggs and egg homogenates. Ca2+ release by NAADP is independent of that induced by either inositol trisphosphate (InsP3) or cyclic adenosine dinucleotide phosphate (cADPR). We now report that in sea urchin egg homogenates, NAADP releases Ca2+ from a Ca2+ pool that is distinct from those that are sensitive to InsP3 and cADPR. This organelle has distinct Ca2+ uptake characteristics: it is insensitive to thapsigargin and cyclopiazoic acid, but maintenance of the pool shows some requirement for ATP. Although the different Ca2+ pools have different characteristics, there appears to be some degree of overlap or cross-talk between the NAADP- and cADPR/InsP3-sensitive Ca2+ pools. Ca(2+)-induced Ca2+ release is unlikely to account for the apparent overlap between stores, since NAADP-induced Ca2+ release, in contrast with that stimulated by cADPR, is not potentiated by bivalent cations.
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17
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Poulsen JC, Caspersen C, Mathiasen D, East JM, Tunwell RE, Lai FA, Maeda N, Mikoshiba K, Treiman M. Thapsigargin-sensitive Ca(2+)-ATPases account for Ca2+ uptake to inositol 1,4,5-trisphosphate-sensitive and caffeine-sensitive Ca2+ stores in adrenal chromaffin cells. Biochem J 1995; 307 ( Pt 3):749-58. [PMID: 7741706 PMCID: PMC1136714 DOI: 10.1042/bj3070749] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
In chromaffin cells of adrenal medulla, heterogeneity of Ca2+ stores has been suggested with respect to the mechanisms of Ca2+ uptake and release. We have examined Ca(2+)-ATPases responsible for loading of Ca2+ stores in these cells for their sensitivity to thapsigargin, a highly selective inhibitor of the SERCA [sarco(endo)plasmic reticulum calcium ATPase] family of intracellular Ca2+ pumps. Using immunostaining, we studied the distribution of Ca(2+)-ATPases, and of receptors for inositol 1,4,5-trisphosphate (InsP3) and ryanodine, in the density-gradient fractions of microsomes from bovine adrenal medulla. In parallel, we examined distribution profiles of ATP-dependent Ca2+ uptake in the same fractions, along with subcellular markers for plasma membranes and endoplasmic reticulum (ER). Two Ca(2+)-ATPase-like proteins (116 and 100 kDa) were detected, consistent with the presence of SERCA 2b and SERCA 3 isoenzymes of Ca2+ pumps. The distribution of these putative Ca(2+)-ATPase iso-enzymes paralleled that of InsP3 and ryanodine receptors. This distribution of ER Ca(2+)-ATPases, as determined immunologically, was consistent with that of thapsigargin-sensitive, but not of thapsigargin-insensitive, ATP-dependent Ca2+ uptake. In contrast, the distribution profile of the thapsigargin-insensitive Ca2+ uptake was strongly correlated to that of plasma membranes, and co-distributed with plasma membrane Ca(2+)-ATPase detected immunologically. In isolated, permeabilized chromaffin cells, InsP3 and caffeine induced Ca2+ release following an ATP-dependent Ca2+ accumulation to the stores. This accumulation was abolished by thapsigargin. Together, these data strongly indicate that the thapsigargin-sensitive, presumably SERCA-type Ca(2+)-ATPases account for Ca2+ uptake to InsP3-sensitive, as well as to caffeine-sensitive, Ca2+ stores in bovine adrenal chromaffin cells.
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Affiliation(s)
- J C Poulsen
- Department of Medical Physiology, Panum Institute, University of Copenhagen, Denmark
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18
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Gagliardino JJ, Rossi JP. Ca(2+)-ATPase in pancreatic islets: its possible role in the regulation of insulin secretion. DIABETES/METABOLISM REVIEWS 1994; 10:1-17. [PMID: 7956672 DOI: 10.1002/dmr.5610100102] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- J J Gagliardino
- CENEXA-Centro de Endocrinología Experimental y Aplicada (UNLP-CONICET), La Plata, Argentina
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19
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Yadav H. Synthesis of spectroscopic studies of oxovanadium(IV) complexes with 16- and 18-membered macrocyclic ligands. Polyhedron 1993. [DOI: 10.1016/s0277-5387(00)81729-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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20
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Eberle J, Reichlmayr-Lais AM, Kirchgessner M. Aktivität der Enzyme Na, K-ATPase und Ca, Mg-ATPase in Milchdrüsen von an Blei depletierten Ratten. J Anim Physiol Anim Nutr (Berl) 1993. [DOI: 10.1111/j.1439-0396.1993.tb00808.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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21
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Benham CD, Evans ML, McBain CJ. Ca2+ efflux mechanisms following depolarization evoked calcium transients in cultured rat sensory neurones. J Physiol 1992; 455:567-83. [PMID: 1484362 PMCID: PMC1175659 DOI: 10.1113/jphysiol.1992.sp019316] [Citation(s) in RCA: 101] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
1. We have used a combination of microfluorimetry and patch-clamp techniques to investigate cytoplasmic Ca2+ ([Ca2+]i) buffering in response to physiological Ca2+ loads in neurones cultured from the dorsal root ganglia of the rat. 2. In cells loaded with Indo-1 AM and using high resistance microelectrodes to initiate and record action potentials, single action potentials were associated with a measurable rise in [Ca2+]i. Short trains of action potentials evoked [Ca2+]i transients with monoexponential recovery rates with time constants of around 5 s. 3. Similar Ca2+ buffering properties were seen in cells perfused with patch-clamp pipettes in the whole-cell recording mode suggesting that the slow (seconds) Ca2+ buffering properties were not seriously perturbed by the recording technique. 4. In cells held under voltage clamp, reversal of the Na(+)-Ca2+ exchanger driving force had a small but significant effect on the rate of Ca2+ removal. 5. Increasing extracellular pH or adding vanadate (200 microM) to the internal solution dramatically slowed the rate of recovery. Addition of calmidazolium to the pipette solution also produced a significant but much less dramatic slowing of Ca2+ efflux. 6. The results demonstrate that the activity of a plasmalemmal Ca(2+)-ATPase is important for the removal of somatic Ca2+ loads of a similar amplitude to those generated by the firing of a few action potentials.
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Affiliation(s)
- C D Benham
- Department of Pharmacology, Smith, Kline & French Research Ltd., Welwyn, Herts
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22
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Abstract
Although vanadium has been of great interest for many researchers over a number of years, its biochemical and physiological role is not yet fully clear. There are many papers describing the haematological consequences of its excess in living organisms and most of their data are quoted in this mini-review. The authors of these papers used various laboratory animals, different vanadium compounds, frequently different routes of administration and duration of intoxication. Hence a checklist and comparison of the results are rather difficult. Vanadium reduces the deformability of erythrocytes, and such cells are rather frequently retained in the reticuloendothelial system of the spleen and eliminated faster from the blood stream (Kogawa et al., 1976). Vanadium produces peroxidative changes in the erythrocyte membrane, this leading to haemolysis. Therefore, the depressed erythrocyte count in animals intoxicated with vanadium may be the consequence of both the haemolytic action of vanadium and the shortened time of survival of erythrocytes. Changes of the haem precursor level in blood serum and urine observed in humans exposed occupationally to vanadium suggest an influence of this element on haem synthesis. This problem requires, however, further studies and observations. Changes occurring under the influence of vanadium on the leukocyte system of animals suggest the influence of this element on the resistance of the organism, but the mechanism of the action of vanadium still requires elucidation.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- H Zaporowska
- Department of Cell Biology, Maria Curie-Skłodowska University, Lublin, Poland
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23
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Cunha VM, Meyer-Fernandes JR, Noël F. A (Ca(2+)-Mg2+)ATPase from Schistosoma mansoni is coupled to an active transport of calcium. Mol Biochem Parasitol 1992; 52:167-73. [PMID: 1535690 DOI: 10.1016/0166-6851(92)90049-p] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The (Ca(2+)-Mg2+)ATPase activity in microsomes of Schistosoma mansoni is fully inhibited by vanadate (I50 = 2.5 microM). 45Ca2+ is accumulated within microsomal vesicles in an ATP-dependent process that is enhanced 5-fold in the presence of 40 mM phosphate. Accumulated 45Ca2+ is rapidly released by 5 microM of the Ca2+ ionophore A23187 (t1/2 less than or equal to 6 s). (Ca(2+)-Mg2+)ATPase activity and Ca2+ uptake share the same subcellular distribution pattern and similar Ca2+ sensitivities (K0.5 = 0.39 microM and 0.15 microM, respectively). The substrate selectivity is high for both ATPase activity and Ca2+ transport. These results indicate the presence of an active transport of Ca2+ coupled to the (Ca(2+)-Mg2+)ATPase activity previously described in this parasite. A plasma membrane localization and physiological role in calcium homeostasis are suggested.
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Affiliation(s)
- V M Cunha
- Departamento de Parasitologia e Biofísica Celular, Universidade Federal do Rio de Janeiro, Brazil
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24
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James-Kracke MR. Calmodulin activation of the Ca2+ pump revealed by fluorescent chelator dyes in human red blood cell ghosts. J Gen Physiol 1992; 99:41-62. [PMID: 1371307 PMCID: PMC2216596 DOI: 10.1085/jgp.99.1.41] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Ca2+ transport in red blood cell ghosts was monitored with fura2 or quin2 incorporated as the free acid during resealing. This is the first report of active transport monitored by the fluorescent intensity of the chelator dyes fura2 (5-50 microM) or quin2 (250 microM) in hemoglobin-depleted ghosts. Since there are no intracellular compartments in ghosts and the intracellular concentrations of all assay chelator substances including calmodulin (CaM), the dyes, and ATP could be set, the intracellular concentrations of free and total Ca [( Cafree]i and [Catotal]i) could be calculated during the transport. Ghosts prepared with or without CaM rapidly extruded Ca2+ to a steady-state concentration of 60-100 nM. A 10(4)-fold gradient for Ca2+ was routinely produced in medium containing 1 mM Ca2+. During active Ca2+ extrusion, d[Cafree]i/dt was a second order function of [Cafree]i and was independent of the dye concentration, whereas d[Catotal]i/dt increased as a first order function of both the [Cafree]i and the concentration of the Ca:dye complex. CaM (5 microM) increased d[Catotal]i/dt by 400% at 1 microM [Cafree]i, while d[Cafree]i/dt increased by only 25%. From a series of experiments we conclude that chelated forms of Ca2+ serve as substrates for the pump under permissive control of the [Cafree]i, and this dual effect may explain cooperativity. Free Ca2+ is extruded, and probably also Ca2+ bound to CaM or other chelators, while CaM and the chelators are retained in the cell.
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Affiliation(s)
- M R James-Kracke
- Department of Pharmacology, University of Missouri-Columbia 65212
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25
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Abstract
1. Magnesium uptake can be measured in ferret red cells incubated in media containing more than 1 mM-magnesium. Uptake is substantially increased if the sodium concentration in the medium is reduced. 2. Magnesium uptake is half-maximally activated by 0.37 mM-external magnesium when the external sodium concentration is 5 mM. Increasing the external sodium concentration increases the magnesium concentration needed to activate the system. 3. Magnesium uptake is increased by reducing the external sodium concentration. Uptake is half-maximum at sodium concentrations of 17, 22 and 62 nM when the external magnesium concentrations are 2, 5 and 10 mM respectively. 4. Replacement of external sodium with choline does not affect the membrane potential of ferret red cells over a 45 min period. 5. Magnesium uptake from media containing 5 mM-sodium is inhibited by amiloride, quinidine and imipramine. It is not affected by ouabain or bumetanide. Vanadate stimulates magnesium uptake but has no effect on magnesium efflux. 6. When cell ATP content is reduced to 19 mumol (1 cell)-1 by incubating cells for 3 h with 2-deoxyglucose, magnesium uptake falls by 50% in the presence of 5 mM-sodium and is completely abolished in the presence of 145 mM-sodium. Some of the inhibition may be due to the increase in intracellular ionized magnesium concentration ([Mg2+]i) from 0.7 to 1.0 mM which occurs under these conditions. 7. Magnesium uptake can be driven against a substantial electrochemical gradient if the external sodium concentration is reduced sufficiently. 8. These findings are discussed in terms of several possible models for magnesium transport. It is concluded that the majority of magnesium uptake observed in low-sodium media is via sodium-magnesium antiport. A small portion of uptake is through a parallel leak pathway. It is believed that the antiport is responsible for maintaining [Mg2+]i below electrochemical equilibrium in these cells at physiological external sodium concentration. Thus in ferret red cells the direction of magnesium transport can be reversed by reversing the sodium gradient.
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Affiliation(s)
- P W Flatman
- Department of Physiology, University Medical School, Edinburgh
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26
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Missiaen L, Wuytack F, Raeymaekers L, De Smedt H, Droogmans G, Declerck I, Casteels R. Ca2+ extrusion across plasma membrane and Ca2+ uptake by intracellular stores. Pharmacol Ther 1991; 50:191-232. [PMID: 1662401 DOI: 10.1016/0163-7258(91)90014-d] [Citation(s) in RCA: 87] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The aim of this review is to summarize the various systems that remove Ca2+ from the cytoplasm. We will initially focus on the Ca2+ pump and the Na(+)-Ca2+ exchanger of the plasma membrane. We will review the functional regulation of these systems and the recent progress obtained with molecular-biology techniques, which pointed to the existence of different isoforms of the Ca2+ pump. The Ca2+ pumps of the sarco(endo)plasmic reticulum will be discussed next, by summarizing the discoveries obtained with molecular-biology techniques, and by reviewing the physiological regulation of these proteins. We will finally briefly review the mitochondrial Ca(2+)-uptake mechanism.
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Affiliation(s)
- L Missiaen
- Laboratory of Molecular Signalling, Department of Zoology, Cambridge, U.K
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27
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Deuticke B, Grebe R, Haest CWM. Action of Drugs on the Erythrocyte Membrane. BLOOD CELL BIOCHEMISTRY 1990. [DOI: 10.1007/978-1-4757-9528-8_16] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
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28
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Missiaen L, Wuytack F, De Smedt H, Amant F, Casteels R. AIF4-induced inhibition of the ATPase activity, the Ca2+-transport activity and the phosphoprotein-intermediate formation of plasma-membrane and endo(sarco)plasmic-reticulum Ca2+-transport ATPases in different tissues. Evidence for a tissue-dependent functional difference. Biochem J 1989; 261:655-60. [PMID: 2528347 PMCID: PMC1138873 DOI: 10.1042/bj2610655] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
AIF4- inhibits the (Ca2+ + Mg2+)-ATPase activity of the plasma-membrane and the sarcoplasmic-reticulum Ca2+-transport ATPase [Missiaen, Wuytack, De Smedt, Vrolix & Casteels (1988) Biochem. J. 253, 827-833]. The aim of the present work was to investigate this inhibition further. We now report that AIF4- inhibits not only the (Ca2+ + Mg2+)-ATPase activity, but also the ATP-dependent 45Ca2+ transport, and the formation of the phosphoprotein intermediate by these pumps. Mg2+ potentiated the effect of AIF4-, whereas K+ had no such effect. The plasma-membrane Ca2+-transport ATPase from erythrocytes was 20 times less sensitive to inhibition by AIF4- as compared with the Ca2+-transport ATPase from smooth muscle. The endoplasmic-reticulum Ca2+-transport ATPase from smooth muscle was inhibited to a greater extent than the sarcoplasmic-reticulum Ca2+-transport ATPase of slow and fast skeletal muscle.
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Affiliation(s)
- L Missiaen
- Department of Physiology, Catholic University of Leuven, Belgium
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29
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Abstract
1. Resealed human red cell ghosts containing lead buffers bring about a net transfer of lead from the cell interior to the outside. This transfer is ATP dependent. 2. The active transport of lead is characterized by a Vmax (maximum velocity) of 11 mmol/(l cells.h) and a KM (Michaelis constant) of 5 x 10(-8) M for internal Pb2+, at pH 6.8 and 37 degrees C. 3. Lead efflux is antagonized by internal calcium, and is inhibited by vanadate with the same IC50 (inhibition constant) with which vanadate inhibits calcium pumping. 4. It is concluded that lead is transported by the calcium pump.
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Affiliation(s)
- T J Simons
- Department of Physiology, King's College London
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30
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Abstract
The influx of 45Ca2+ into normal red cells and various types of spherocytic red cells was studied after blocking active Ca2+ extrusion by vanadate. The measurements were performed with and without verapamil, a calcium antagonist. The influx of Ca2+ into red cells from unsplenectomized persons was 22 +/- 7 mumol/l packed red cells/h (mean +/- SD), and 17 +/- 7 mumol/l per h when incubated with verapamil. The influx of Ca2+ into red cells from four splenectomized normal controls was of the same magnitude as in the unsplenectomized controls but there was no effect of verapamil on the influx rate. The influx of Ca2+ into red cells from nine splenectomized patients with hereditary spherocytosis (HS) was 27 +/- 9 mumol/l per h without and 24 +/- 9 mumol/l per h with verapamil. In 9 normal red cell samples made spherocytic by thermal damage the corresponding values were 32 +/- 16 and 31 +/- 19 mumol/l per h, respectively. The uptake of Ca2+ in chlorpromazine-induced spherocytic red cells was 20 +/- 4 mumol/l per h without and 19 +/- 5 mumol/l per h with verapamil in 9 experiments. These results indicate that although in HS erythrocytes changes in the cell membrane lead to an increased Ca2+ influx, the slow calcium channels are not affected, whereas in spherocytes induced by thermal damage or by incubation with chlorpromazine the channels are blocked, at least partly.
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Affiliation(s)
- R Johnsson
- Laakso Hospital, City of Helsinki, Finland
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31
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Abstract
In this communication, an ATP-dependent Ca2+ uptake was characterized in term human placental brush border membranes. Multiple freeze-thaw cycles greatly diminished uptake activity by 90 per cent, indicating an intravesicular accumulation of Ca2+. Kinetic studies indicate an apparent Km for Ca2+ of 0.22 +/- 0.04 microM and a Vmax of 441 +/- 137 pmoles/min/mg protein at 37 degrees C. The uptake was shown to have an optimum pH between 7.0 and 7.2, and was unaffected by the addition of oxalate, characteristics which are consistent with a plasma membrane origin of uptake. The process was temperature-dependent with a Q10 of 1.11 and was significantly inhibited (50 per cent) by 100 microM concentrations of trifluoperazine and vanadate. The characteristics of placental brush border Ca2+ uptake are similar to those of other Ca2+ uptake systems known to regulate intracellular calcium concentrations. By analogy, we suggest a similar role for this process in the maintenance of the low intracellular Ca2+ levels necessary for placental syncytiotrophoblast viability.
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Affiliation(s)
- K A Treinen
- Department of Anatomy and Cell Biology, University of Michigan, Ann Arbor 48109
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32
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Sarkadi B, Enyedi A, Gárdos G. Conformational changes of the in situ red cell membrane calcium pump affect its proteolysis. BIOCHIMICA ET BIOPHYSICA ACTA 1987; 899:129-33. [PMID: 2952170 DOI: 10.1016/0005-2736(87)90247-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
In inside-out red cell membrane vesicles trypsin digestion reduces the molecular mass of the 32P-labeled acyl-phosphate intermediate of the calcium pump from the original 140 kDa to about 80 kDa with a simultaneous activation of the calcium uptake. This process is slightly stimulated by the presence of calcium, as compared to EGTA, or EGTA + vanadate, but the proteolytic pattern is similar under all these conditions. However, trypsin degradation of the 80 kDa polypeptide, resulting in the loss of calcium transport activity and 32P-phosphoenzyme formation, is rapid in the presence of calcium, inhibited by EGTA and almost fully blocked by EGTA + vanadate. In the presence of these latter ligands, probably locking the calcium pump in an E2 conformation, the 80 kDa protein becomes insensitive even to excessive digestion by the non-specific protease, pronase. The data indicate major changes in the molecular arrangement of the calcium pump protein when transformed from a calcium-liganded (E1) to an E2 conformation.
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33
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Palmer LG. Modulation of apical Na permeability of the toad urinary bladder by intracellular Na, Ca, and H. J Membr Biol 1985; 83:57-69. [PMID: 3923198 DOI: 10.1007/bf01868738] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
The Na conductance of the apical membrane of the toad urinary bladder was measured at different concentrations of Na both in the external medium and in the cell. Bladders were bathed in high K-sucrose medium to reduce basal-lateral resistance and voltage, and the transepithelial currents measured under voltage-clamp conditions. Amiloride was used as a specific blocker of the apical Na channel. At constant external Na, the internal Na concentration was increased by blocking the basal-lateral Na pump with ouabain. With high Na activity in the mucosal medium (86 mM), increases in intracellular Na activity from 10 to over 40 mM increased the amiloride-sensitive slope conductance at zero voltage while apical Na permeability, estimated from current-voltage plots using the constant field equation, decreased by less than 20%. Lowering the serosal Ca concentration from 1 to 0.1 mM had no effect on the change in PNa with increasing Nac, but increasing serosal Ca to 5 mM enhanced the reduction in PNa with increasing Nac, presumably by increasing Ca influx into the cell. PNa was also reduced by serosal vanadate (0.5 mM), a putative blocker of ATP-dependent Ca extrusion from the cell, and by acute exposure to CO2, which presumably acidifies the cytoplasm. Current-voltage relationships of the amiloride-sensitive transport pathway were also measured in the absence of a Na gradient across the apical membrane. These plots show that outward current passes through the channels somewhat less easily than does inward current. The shape of the I-V relationships was not significantly altered by changes in cellular Na, Ca or H, indicating that the effects of these ions on PNa are voltage independent.
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34
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Proffitt R, Case RM. The effects of vanadate on 45Ca exchange and enzyme secretion in the rat exocrine pancreas. Cell Calcium 1984; 5:321-34. [PMID: 6207927 DOI: 10.1016/0143-4160(84)90001-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
The effects of vanadate on calcium homeostasis and enzyme secretion have been assessed in the incubated pancreas of young rats. Vanadate causes an acceleration of 45Ca efflux from pre-loaded uncinate glands; amylase release is reversibly increased for the duration of exposure to vanadate. Alkaline orthovanadate is most effective in eliciting these responses; its effects are greatly reduced at pH 7.4. However, changes in pH alone do not mimic these effects. Other vanadium oxides (meta-vanadate, vanadium pentoxide and vanadyl sulphate) are poor secretagogues. Alkaline ortho-, or meta-vanadate also causes an increased calcium uptake although this does not seem to be responsible for the observed secretory response. Vanadate is thought to stimulate pancreatic secretion by an effect on intracellular calcium store(s).
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35
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Erdmann E, Werdan K, Krawietz W, Schmitz W, Scholz H. Vanadate and its significance in biochemistry and pharmacology. Biochem Pharmacol 1984; 33:945-50. [PMID: 6324815 DOI: 10.1016/0006-2952(84)90498-2] [Citation(s) in RCA: 66] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
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36
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Fuhrmann GF, Hüttermann J, Knauf PA. The mechanism of vanadium action on selective K+-permeability in human erythrocytes. BIOCHIMICA ET BIOPHYSICA ACTA 1984; 769:130-40. [PMID: 6419778 DOI: 10.1016/0005-2736(84)90016-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Low concentrations of chelating agents such as EDTA prevent the air oxidation of vanadyl (VO2+, +4 oxidation state) to vanadate (VO3-, +5 oxidation state). Under these conditions, the ionophore A23187 mediates the rapid entry of vanadyl into human erythrocytes. In the presence of A23187, vanadyl at concentrations in excess of EDTA gives rise to a dramatic increase in K+ permeability, which is very similar to the Gardos Ca2+-induced K+ permeability increase with respect to ion selectivity, response to inhibitors, effects of pH, and stimulation by external K+. In ultrapure media with very low Ca2+, however, vanadyl has no effect on K+ permeability. These experiments suggest that Ca2+ is displaced from EDTA by vanadyl and then enters the cell via A23187 where it triggers the increase in K+ permeability. This hypothesis is confirmed by experiments demonstrating that vanadyl does displace Ca2+ from EDTA. Vanadate, an inhibitor of Ca2+-ATPase, causes a selective increase in K+ permeability in metabolically depleted cells, but the increase is abolished by low concentrations of EDTA, indicating that this effect is also due to entry of extracellular Ca2+. Earlier observations of effects of vanadyl and vanadate on erythrocyte K+ permeability can thus be explained on the basis of inhibition of the Ca2+ pump by vanadium, leading to an increase in intracellular Ca2+ concentration.
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Klaven NB, Pershadsingh HA, Henius GV, Laris PC, Long JW, McDonald JM. A high-affinity, calmodulin-sensitive (Ca2+ + Mg2+)-ATPase and associated calcium-transport pump in the Ehrlich ascites tumor cell plasma membrane. Arch Biochem Biophys 1983; 226:618-28. [PMID: 6139089 DOI: 10.1016/0003-9861(83)90331-4] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
A unique cytoplast preparation from Ehrlich ascites tumor cells (G. V. Henius, P. C. Laris, and J. D. Woodburn (1979) Exp. Cell. Res. 121, 337-345), highly enriched in plasma membranes, was employed to characterize the high-affinity plasma membrane calcium-extrusion pump and its associated adenosine triphosphatase (ATPase). An ATP-dependent calcium-transport system which had a high affinity for free calcium (K0.5 = 0.040 +/- 0.005 microM) was identified. Two different calcium-stimulated ATPase activities were detected. One had a low (K0.5 = 136 +/- 10 microM) and the other a high (K0.5 = 0.103 +/- 0.077 microM) affinity for free calcium. The high-affinity enzyme appeared to represent the ubiquitous high-affinity plasma membrane (Ca2+ + Mg2+)-ATPase (calcium-stimulated, magnesium-dependent ATPase) seen in normal cells. Both calcium transport and the (Ca2+ + Mg2+)-ATPase were significantly stimulated by the calcium-dependent regulatory protein calmodulin, especially when endogenous activator was removed by treatment with the calcium chelator ethylene glycol bis(beta-aminoethyl ether) N,N'-tetraacetic acid. Other similarities between calcium transport and the (Ca2+ + Mg2+)-ATPase included an insensitivity to ouabain (0.5 mM), lack of activation by potassium (20 mM), and a requirement for magnesium. These similar properties suggested that the (Ca2+ + Mg2+)-ATPase represents the enzymatic basis of the high-affinity calcium pump. The calcium pump/enzyme system was inhibited by orthovanadate at comparatively high concentrations (calcium transport: K0.5 congruent to 100 microM; (Ca2+ + Mg2+)-ATPase: K0.5 greater than 100 microM). Upon Hill analysis, the tumor cell (Ca2+ + Mg2+)-ATPase failed to exhibit cooperative activation by calcium which is characteristic of the analogous enzyme in the plasma membrane of normal cells.
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Ueda T. Na+-Ca2+ exchange activity in rabbit lymphocyte plasma membranes. BIOCHIMICA ET BIOPHYSICA ACTA 1983; 734:342-6. [PMID: 6615836 DOI: 10.1016/0005-2736(83)90133-5] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Plasma membranes of rabbit thymus lymphocytes accumulated Ca2+ when a Na+ gradient (intravesicular greater than extravesicular) was formed across the membranes. Dissipation of the Na+ gradient by the addition of Na+ to the external medium decreased Ca2+ uptake. Ca2+ preloaded into the lymphocytes was extruded when Na+ was added to the external medium. The Ca2+ uptake decreased at acidic pH but increased at alkaline pH (above 8) and the activity was saturable for Ca2+ (apparent Km for Ca2+ was 61 microM and apparent Vmax was 11.5 nmol/mg protein per min). Na+-dependent uptake of Ca2+ was inhibited by tetracaine and verapamil, and partially inhibited by La3+. The uptake was not influenced by orthovanadate.
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Abstract
Vanadium is distributed extensively in nature. It is a trace element and is present in almost all living organisms including man. Even though vanadium was originally recognized for its ability to inhibit membrane Na+-K+-ATPase, various laboratory studies now document that this element has the capacity to affect the activity of various intracellular enzyme systems and may modify their physiological functions. Vanadium may be an essential element for normal development and may play an important role in various homeostatic mechanisms, and thus vanadium deficiency may prove to be an important concern. Abnormalities in biological disposition of vanadium may be involved in the pathogenesis of certain neurological disorders or cardiovascular diseases. While the essentiality of this element for living organisms is yet to be established with certainty, vanadium has become an increasingly important element and is used extensively in various heavy industries such as steel, oil, etc.; thus, the incidence of exposure to toxic levels of vanadium to industrial workers has been an increasing concern for toxicologists. To date, little information is available on the physiological or pharmacological actions of vanadium; hence, it is difficult to reach any definitive conclusion concerning its biological significance, essentiality and its role in pathological states. An attempt has been made in this review to broadly document what is known of various biological actions of vanadium.
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Akerman KE, Proudlove MO, Moore AL. Evidence for a Ca2+ gradient across the plasma membrane of wheat protoplasts. Biochem Biophys Res Commun 1983; 113:171-7. [PMID: 6407477 DOI: 10.1016/0006-291x(83)90447-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Fluxes of Ca2+ across the plasma membrane of isolated wheat protoplasts have been measured both as net accumulation and as uptake under steady-state conditions. The ATPase inhibitors, orthovanadate and diethylstibesterol, and the divalent cation ionophore, A23187, were all found to enhance net Ca2+ accumulation by protoplasts. The uptake of Ca2+ under steady-state conditions was also stimulated by A23187 but relatively unaffected by a range of plant hormones or by red or far red light. Light treatments were compared to dark controls with protoplasts isolated from etiolated wheat. The results suggest that plant cells maintain a Ca2+ gradient across their plasma membrane but it appears not to be under phytochrome control.
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Kratje RB, Garrahan PJ, Rega AF. The effects of alkali metal ions on active Ca2+ transport in reconstituted ghosts from human red cells. BIOCHIMICA ET BIOPHYSICA ACTA 1983; 731:40-6. [PMID: 6849910 DOI: 10.1016/0005-2736(83)90395-4] [Citation(s) in RCA: 33] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
1. K+, Rb+ or Na+ increase from 30 to 90% the maximum rate of Ca2+ transport from resealed ghosts, leaving unaltered the apparent affinity of the Ca2+ pump for Ca2+. Li+ is ineffective as activator of Ca2+ transport. 2. K+ does not change the temperature dependence of Ca2+ transport. 3. The effects of K+ and Na+ are half-maximal at 4.6 mM and 24 mM, respectively. 4. The site(s) at which K+ or Na+ combine are accessible only from the cytoplasmic surface of the cell membrane. 5. Under conditions in which Na+ activates the Ca2+ pump no Na+ efflux coupled to Ca2+ efflux is apparent.
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Abstract
1. In inside-out vesicles of high potassium permeability, prepared from human red cell membranes, volume changes accompanying the action of the Ca2+ pump were measured by recording the intensity of light scattered by a suspension of these vesicles. Replacing Cl- by the impermeant gluconate anion changed swelling into shrinking. 2. Assuming that in Cl- media two Cl- ions accompany one Ca+ ion moved by the pump and in gluconate media two K+ ions are exchanged for one Ca2+ ion resulted in a good agreement between relative Ca2+ transport rate obtained from the volume change and from direct measurement of 45Ca uptake in the two media. 3. The fact that it is possible to change co-transport of Ca with Cl- into counter-transport of Ca2+ for K+ rules out that within the pump there is an obligatory coupling of Ca2+ movement with movement of another ion species (including the proton). The conclusion, therefore, is that the Ca2+ pump must be electrogenic. 4. The combination of measurement of volume change with direct measurement of 45Ca movement yielded 5-6 microliter/mg protein for the volume of the vesicles.
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Abstract
Intracellular calcium regulates a number of membrane functions in the erythrocyte, including control of shape, membrane lipid composition and cation permeability. Measurement of total red cell calcium has yielded values between 5 and 15 nmol/ml cells, and these low values in part reflect the absence of Ca2+ -containing organelles. Most intracellular Ca2+ is bound and the low cell ionized Ca2+ concentration (approximately 0.2 microM) is maintained by a combination of low membrane permeability and a powerful Ca2+ -pump. This pump has been identified with a (Ca2+ + Mg2+)-stimulated ATPase, and both Ca2+ transport and ATP splitting are stimulated by calmodulin, a low molecular weight protein which binds Ca2+ avidly and activates many Ca2+ -dependent enzymes. Both high and low affinity kinetics for Ca2+ pumping have been demonstrated, depending on the extent of binding of calmodulin to the pump. A stoichiometry of either 1 or 2 Ca2+ ions pumped per ATP molecule split has been shown, and the value may vary with the level of intracellular Ca2+. Phenothiazines, such as chlorpromazine inhibit the Ca2+ -pump by antagonizing the increment in activity produced by calmodulin. The passive inward leak of Ca2+ into erythrocytes can be quantitated by 45Ca2+ uptake into red cells whose Ca2+ -pump has been inhibited. Estimates of the Ca2+ permeability, based on unidirectional influx, yield values many orders of magnitude lower than for nucleated cells. Influx of Ca2+ into human erythrocytes occurs by a facilitated diffusion process, which can be inhibited by phenothiazines and the cinchona alkaloids. Calcium affects many membrane functions including cation permeability, lipid composition and some cytoskeletal interactions which may determine cell shape. Any rise in intracellular Ca2+ activates a specific K+ channel which normally makes little contribution to K+ fluxes. Kinetic studies of this process demonstrate either high or low affinity Ca2+ -activation of K+ efflux, with low affinity of the channel to Ca2+ being the probable state in vivo. Propranolol is the best known activator of Ca2+ -stimulated K+ efflux, although the mechanism of stimulation is unclear. Like other tissues, red cells possess a Ca2+ -activated phosphoinositol phosphodiesterase. Although it has been suggested that the echinocytic shape change induced by Ca2+ is due to the hydrolysis of polyphosphoinositides, it seems more likely that this shape change results from an effect of Ca2+ on the macromolecular interactions of the cytoskeleton. Abnormal Ca2+ permeability may contribute to red cell destruction in a variety of diseases. For example, in sickle cell anemia a large Ca2+ influx occurs when cells are sickled under deoxy conditions, and moreover, the ability of the Ca2+ -pump to extrude the increment of cell Ca2+ is impaired. Thus, red cell Ca2+ is increased 3-7-fold above normal and this may contribute to the short survival of sickle red cells...
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