1
|
Expression of plasma membrane calcium ATPases confers Ca 2+/H + exchange in rodent synaptic vesicles. Sci Rep 2019; 9:4289. [PMID: 30862855 PMCID: PMC6414521 DOI: 10.1038/s41598-019-40557-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 02/19/2019] [Indexed: 02/07/2023] Open
Abstract
Ca2+ transport into synaptic vesicles (SVs) at the presynaptic terminals has been proposed to be an important process for regulating presynaptic [Ca2+] during stimulation as well as at rest. However, the molecular identity of the transport system remains elusive. Previous studies have demonstrated that isolated SVs exhibit two distinct Ca2+ transport systems depending on extra-vesicular (cytosolic) pH; one is mediated by a high affinity Ca2+ transporter which is active at neutral pH and the other is mediated by a low affinity Ca2+/H+ antiporter which is maximally active at alkaline pH of 8.5. In addition, synaptic vesicle glycoprotein 2 s (SV2s), a major SV component, have been proposed to contribute to Ca2+ clearance from the presynaptic cytoplasm. Here, we show that at physiological pH, the plasma membrane Ca2+ ATPases (PMCAs) are responsible for both the Ca2+/H+ exchange activity and Ca2+ uptake into SVs. The Ca2+/H+ exchange activity monitored by acidification assay exhibited high affinity for Ca2+ (Km ~ 400 nM) and characteristic divalent cation selectivity for the PMCAs. Both activities were remarkably reduced by PMCA blockers, but not by a blocker of the ATPase that transfers Ca2+ from the cytosol to the lumen of sarcoplasmic endoplasmic reticulum (SERCA) at physiological pH. Furthermore, we rule out the contribution of SV2s, putative Ca2+ transporters on SVs, since both Ca2+/H+ exchange activity and Ca2+ transport were unaffected in isolated vesicles derived from SV2-deficient brains. Finally, using a PMCA1-pHluorin construct that enabled us to monitor cellular distribution and recycling properties in living neurons, we demonstrated that PMCA1-pHluorin localized to intracellular acidic compartments and recycled at presynaptic terminals in an activity-dependent manner. Collectively, our results imply that vesicular PMCAs may play pivotal roles in both presynaptic Ca2+ homeostasis and the modulation of H+ gradient in SVs.
Collapse
|
2
|
Abstract
Cellular membranes display a diversity of functions that are conferred by the unique composition and organization of their proteins and lipids. One important aspect of lipid organization is the asymmetric distribution of phospholipids (PLs) across the plasma membrane. The unequal distribution of key PLs between the cytofacial and exofacial leaflets of the bilayer creates physical surface tension that can be used to bend the membrane; and like Ca2+, a chemical gradient that can be used to transduce biochemical signals. PL flippases in the type IV P-type ATPase (P4-ATPase) family are the principle transporters used to set and repair this PL gradient and the asymmetric organization of these membranes are encoded by the substrate specificity of these enzymes. Thus, understanding the mechanisms of P4-ATPase substrate specificity will help reveal their role in membrane organization and cell biology. Further, decoding the structural determinants of substrate specificity provides investigators the opportunity to mutationally tune this specificity to explore the role of particular PL substrates in P4-ATPase cellular functions. This work reviews the role of P4-ATPases in membrane biology, presents our current understanding of P4-ATPase substrate specificity, and discusses how these fundamental aspects of P4-ATPase enzymology may be used to enhance our knowledge of cellular membrane biology.
Collapse
Affiliation(s)
- Bartholomew P. Roland
- Vanderbilt University, Department of Biological Sciences, 1161 21st Ave South, Nashville, TN 37235
| | - Todd R. Graham
- Vanderbilt University, Department of Biological Sciences, 1161 21st Ave South, Nashville, TN 37235
| |
Collapse
|
3
|
Kerr DJ, Marsillo A, Guariglia SR, Budylin T, Sadek R, Menkes S, Chauhan A, Wen GY, McCloskey DP, Wieraszko A, Banerjee P. Aberrant hippocampal Atp8a1 levels are associated with altered synaptic strength, electrical activity, and autistic-like behavior. Biochim Biophys Acta Mol Basis Dis 2016; 1862:1755-65. [PMID: 27287255 DOI: 10.1016/j.bbadis.2016.06.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Revised: 05/06/2016] [Accepted: 06/05/2016] [Indexed: 12/18/2022]
Abstract
Type IV ATPases are putative aminophospholipid translocases (APLTs), more commonly known as flippases. A pronounced induction of the flippase Atp8a1 was observed in post-mortem tissue homogenates from the hippocampus and temporal lobe of juvenile autistic subjects compared to age-matched controls. In order to simulate the human data, C57BL/6 mice were allowed to develop after intra-hippocampal injection of recombinant lentivirus expressing Atp8a1 at the early developmental stage of postnatal day 6 (P6). Transmission electron microscopy (TEM) analysis of the lentivirus-Atp8a1 treated (Atp8a1+) mice in adulthood revealed fewer and weaker excitatory synapses in the hippocampal CA1 region compared to mice injected with empty virus. Significant inhibition of the Schaffer collateral pathway was observed in the Atp8a1+ mice in paired-pulse recording (PPR) at 20-ms inter-stimulus interval. In the three-chambered sociability test, the Atp8a1+ mice displayed no preference for an encaged stranger mouse over a novel object, which is a characteristic autistic-like behavior. In sharp contrast, Atp8a1 (-/-) mice displayed a preference for a stranger mouse over the novel object, which is characteristic of neurotypical mouse behavior. However, similar to the Atp8a1+ mice, the Atp8a1 (-/-) mice harbored fewer and weaker excitatory synapses in CA1 compared to wild-type controls, and displayed inhibition at 20-ms inter-stimulus interval in PPR. These findings suggest that both elevated and diminished levels of Atp8a1 during early development are detrimental to brain connectivity, but only elevated Atp8a1 is associated with aberrant social behavior. Mice with augmented levels of Atp8a1 may therefore serve as a potential model in autism research.
Collapse
Affiliation(s)
- Daniel J Kerr
- Doctoral Program in Biology (CUNY), The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Alexandra Marsillo
- Doctoral Program in Biology (CUNY), The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Sara R Guariglia
- Department of Environmental Health Sciences, Mailman School of Public Health, Columbia University, New York, NY, United States
| | - Tatyana Budylin
- Doctoral Program in Biology (CUNY), The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Rodina Sadek
- Center for Developmental Neuroscience, The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Silvia Menkes
- Center for Developmental Neuroscience, The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Abha Chauhan
- New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, United States
| | - Guang Y Wen
- Center for Developmental Neuroscience, The College of Staten Island (CUNY), Staten Island, NY 10314, United States; New York State Institute for Basic Research in Developmental Disabilities, Staten Island, NY 10314, United States
| | - Daniel P McCloskey
- Doctoral Program in Psychology, CUNY Graduate Center, New York, NY 10016, United States; Center for Developmental Neuroscience, The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Andrzej Wieraszko
- Department of Biology, The College of Staten Island (CUNY), Staten Island, NY 10314, United States; Center for Developmental Neuroscience, The College of Staten Island (CUNY), Staten Island, NY 10314, United States
| | - Probal Banerjee
- Doctoral Program in Biology (CUNY), The College of Staten Island (CUNY), Staten Island, NY 10314, United States; Department of Chemistry, The College of Staten Island (CUNY), Staten Island, NY 10314, United States; Center for Developmental Neuroscience, The College of Staten Island (CUNY), Staten Island, NY 10314, United States.
| |
Collapse
|
4
|
Montigny C, Lyons J, Champeil P, Nissen P, Lenoir G. On the molecular mechanism of flippase- and scramblase-mediated phospholipid transport. Biochim Biophys Acta Mol Cell Biol Lipids 2015; 1861:767-783. [PMID: 26747647 DOI: 10.1016/j.bbalip.2015.12.020] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Revised: 12/20/2015] [Accepted: 12/28/2015] [Indexed: 11/20/2022]
Abstract
Phospholipid flippases are key regulators of transbilayer lipid asymmetry in eukaryotic cell membranes, critical to many trafficking and signaling pathways. P4-ATPases, in particular, are responsible for the uphill transport of phospholipids from the exoplasmic to the cytosolic leaflet of the plasma membrane, as well as membranes of the late secretory/endocytic pathways, thereby establishing transbilayer asymmetry. Recent studies combining cell biology and biochemical approaches have improved our understanding of the path taken by lipids through P4-ATPases. Additionally, identification of several protein families catalyzing phospholipid 'scrambling', i.e. disruption of phospholipid asymmetry through energy-independent bi-directional phospholipid transport, as well as the recent report of the structure of such a scramblase, opens the way to a deeper characterization of their mechanism of action. Here, we discuss the molecular nature of the mechanism by which lipids may 'flip' across membranes, with an emphasis on active lipid transport catalyzed by P4-ATPases. This article is part of a Special Issue entitled: The cellular lipid landscape edited by Tim P. Levine and Anant K. Menon.
Collapse
Affiliation(s)
- Cédric Montigny
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Joseph Lyons
- DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Philippe Champeil
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France
| | - Poul Nissen
- DANDRITE, Nordic-EMBL Partnership for Molecular Medicine, and PUMPkin, Danish National Research Foundation, Aarhus University, Department of Molecular Biology and Genetics, Gustav Wieds Vej 10C, 8000 Aarhus C, Denmark
| | - Guillaume Lenoir
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ Paris-Sud, Université Paris-Saclay, 91198 Gif-sur-Yvette, France.
| |
Collapse
|
5
|
Coleman JA, Quazi F, Molday RS. Mammalian P4-ATPases and ABC transporters and their role in phospholipid transport. Biochim Biophys Acta Mol Cell Biol Lipids 2012; 1831:555-74. [PMID: 23103747 DOI: 10.1016/j.bbalip.2012.10.006] [Citation(s) in RCA: 102] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Revised: 10/16/2012] [Accepted: 10/18/2012] [Indexed: 02/08/2023]
Abstract
Transport of phospholipids across cell membranes plays a key role in a wide variety of biological processes. These include membrane biosynthesis, generation and maintenance of membrane asymmetry, cell and organelle shape determination, phagocytosis, vesicle trafficking, blood coagulation, lipid homeostasis, regulation of membrane protein function, apoptosis, etc. P(4)-ATPases and ATP binding cassette (ABC) transporters are the two principal classes of membrane proteins that actively transport phospholipids across cellular membranes. P(4)-ATPases utilize the energy from ATP hydrolysis to flip aminophospholipids from the exocytoplasmic (extracellular/lumen) to the cytoplasmic leaflet of cell membranes generating membrane lipid asymmetry and lipid imbalance which can induce membrane curvature. Many ABC transporters play crucial roles in lipid homeostasis by actively transporting phospholipids from the cytoplasmic to the exocytoplasmic leaflet of cell membranes or exporting phospholipids to protein acceptors or micelles. Recent studies indicate that some ABC proteins can also transport phospholipids in the opposite direction. The importance of P(4)-ATPases and ABC transporters is evident from the findings that mutations in many of these transporters are responsible for severe human genetic diseases linked to defective phospholipid transport. This article is part of a Special Issue entitled Phospholipids and Phospholipid Metabolism.
Collapse
Affiliation(s)
- Jonathan A Coleman
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, B.C., Canada
| | | | | |
Collapse
|
6
|
Sebastian TT, Baldridge RD, Xu P, Graham TR. Phospholipid flippases: building asymmetric membranes and transport vesicles. Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1821:1068-77. [PMID: 22234261 DOI: 10.1016/j.bbalip.2011.12.007] [Citation(s) in RCA: 173] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 12/14/2011] [Accepted: 12/16/2011] [Indexed: 01/25/2023]
Abstract
Phospholipid flippases in the type IV P-type ATPase family (P4-ATPases) are essential components of the Golgi, plasma membrane and endosomal system that play critical roles in membrane biogenesis. These pumps flip phospholipid across the bilayer to create an asymmetric membrane structure with substrate phospholipids, such as phosphatidylserine and phosphatidylethanolamine, enriched within the cytosolic leaflet. The P4-ATPases also help form transport vesicles that bud from Golgi and endosomal membranes, thereby impacting the sorting and localization of many different proteins in the secretory and endocytic pathways. At the organismal level, P4-ATPase deficiencies are linked to liver disease, obesity, diabetes, hearing loss, neurological deficits, immune deficiency and reduced fertility. Here, we review the biochemical, cellular and physiological functions of P4-ATPases, with an emphasis on their roles in vesicle-mediated protein transport. This article is part of a Special Issue entitled Lipids and Vesicular Transport.
Collapse
Affiliation(s)
- Tessy T Sebastian
- Department of Biological Sciences, Vanderbilt University, Nashville TN 37235, USA
| | | | | | | |
Collapse
|
7
|
Levano K, Punia V, Raghunath M, Debata PR, Curcio GM, Mogha A, Purkayastha S, McCloskey D, Fata J, Banerjee P. Atp8a1 deficiency is associated with phosphatidylserine externalization in hippocampus and delayed hippocampus-dependent learning. J Neurochem 2011; 120:302-13. [PMID: 22007859 DOI: 10.1111/j.1471-4159.2011.07543.x] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The molecule responsible for the enzyme activity plasma membrane (PM) aminophospholipid translocase (APLT), which catalyzes phosphatidylserine (PS) translocation from the outer to the inner leaflet of the plasma membrane, is unknown in mammals. A Caenorhabditis elegans study has shown that ablation of transbilayer amphipath transporter-1 (TAT-1), which is an ortholog of a mammalian P-type ATPase, Atp8a1, causes PS externalization in the germ cells. We demonstrate here that the hippocampal cells of the dentate gyrus, and Cornu Ammonis (CA1, CA3) in mice lacking Atp8a1 exhibit a dramatic increase in PS externalization. Although their hippocampi showed no abnormal morphology or heightened apoptosis, these mice displayed increased activity and a marked deficiency in hippocampus-dependent learning, but no hyper-anxiety. Such observations indicate that Atp8a1 plays a crucial role in PM-APLT activity in the neuronal cells. In corroboration, ectopic expression of Atp8a1 but not its close homolog, Atp8a2, caused an increase in the population (V(max) ) of PM-APLT without any change in its signature parameter K(m) in the neuronal N18 cells. Conversely, expression of a P-type phosphorylation-site mutant of Atp8a1 (Atp8a1*) caused a decrease in V(max) of PM-APLT without significantly altering its K(m) . The Atp8a1*-expressing N18 cells also exhibited PS externalization without apoptosis. Together, our data strongly indicate that Atp8a1 plays a central role in the PM-APLT activity of some mammalian cells, such as the neuronal N18 and hippocampal cells.
Collapse
Affiliation(s)
- Kelly Levano
- CUNY Doctoral Program in Biochemistry, City University of New York at the College of Staten Island, Staten Island, New York, USA
| | | | | | | | | | | | | | | | | | | |
Collapse
|
8
|
Affiliation(s)
- Michael G. Palmgren
- Center for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, University of Copenhagen, DK-1871 Frederiksberg C, Denmark;
| | - Poul Nissen
- Center for Membrane Pumps in Cells and Disease – PUMPKIN, Danish National Research Foundation, Aarhus University, DK-8000 Århus C, Denmark;
| |
Collapse
|
9
|
Wang J, Sun F, Zhang DW, Ma Y, Xu F, Belani JD, Cohen JC, Hobbs HH, Xie XS. Sterol transfer by ABCG5 and ABCG8: in vitro assay and reconstitution. J Biol Chem 2006; 281:27894-904. [PMID: 16867993 PMCID: PMC4527585 DOI: 10.1074/jbc.m605603200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
ATP-binding cassette transporters G5 and G8 are half-transporters expressed on the apical membranes of enterocytes and hepatocytes that limit intestinal uptake and promote secretion of neutral sterols. Genetic defects that inactivate either half-transporter cause accumulation of cholesterol and plant sterols, resulting in premature coronary atherosclerosis. These observations suggest that G5 and G8 promote the translocation of sterols across membranes, but the primary transport substrate of the G5G8 complex has not been directly determined. Here we report the development of a sterol transfer assay using "inside-out" membrane vesicles from Sf9 cells expressing recombinant mouse G5 and G8. Radiolabeled cholesterol or sitosterol was transferred from donor liposomes to G5- and G8-containing membrane vesicles in an ATP-dependent and vanadate-sensitive manner; net transfer of cholesterol was associated with an increase in vesicular cholesterol mass. CTP, GTP, and UTP, as well as ATP, supported transfer but with lesser efficiency (ATP >> CTP > GTP > UTP). Transfer was specific for sterols and was stereoselective; minimal ATP-dependent and vanadate-sensitive transfer of cholesteryl oleate, phosphatidylcholine, or enantiomeric cholesterol was observed. These studies indicate that G5 and G8 are sufficient for reconstitution of sterol transfer activity in vitro and provide the first demonstration that sterols are direct transport substrates of the G5 and G8 heterodimer.
Collapse
Affiliation(s)
- Jin Wang
- Eugene McDermott Center for Human Growth and Development, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-8591
| | - Fang Sun
- Eugene McDermott Center for Human Growth and Development, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-8591
| | - Da-wei Zhang
- Eugene McDermott Center for Human Growth and Development, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-8591
| | - Yongming Ma
- Eugene McDermott Center for Human Growth and Development, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-8591
| | - Fang Xu
- Center of Human Nutrition, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-8591
| | - Jitendra D. Belani
- Department of Chemistry, University of California, Irvine, California 92697-2025
| | - Jonathan C. Cohen
- Eugene McDermott Center for Human Growth and Development, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-8591
- Center of Human Nutrition, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-8591
- Department of Internal Medicine, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-8591
| | - Helen H. Hobbs
- Eugene McDermott Center for Human Growth and Development, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-8591
- Department of Internal Medicine, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-8591
- Howard Hughes Medical Institute and Department of Molecular Genetics, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-8591
| | - Xiao-Song Xie
- Eugene McDermott Center for Human Growth and Development, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-8591
- Department of Internal Medicine, the University of Texas Southwestern Medical Center, Dallas, Texas 75390-8591
- To whom correspondence should be addressed. Tel.: 214-648-7700; Fax: 214-648-7720;
| |
Collapse
|
10
|
Kagan VE, Borisenko GG, Tyurina YY, Tyurin VA, Jiang J, Potapovich AI, Kini V, Amoscato AA, Fujii Y. Oxidative lipidomics of apoptosis: redox catalytic interactions of cytochrome c with cardiolipin and phosphatidylserine. Free Radic Biol Med 2004; 37:1963-85. [PMID: 15544916 DOI: 10.1016/j.freeradbiomed.2004.08.016] [Citation(s) in RCA: 271] [Impact Index Per Article: 13.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/17/2004] [Revised: 08/24/2004] [Accepted: 08/26/2004] [Indexed: 12/16/2022]
Abstract
The primary life-supporting function of cytochrome c (cyt c) is control of cellular energetic metabolism as a mobile shuttle in the electron transport chain of mitochondria. Recently, cyt c's equally important life-terminating function as a trigger and regulator of apoptosis was identified. This dreadful role is realized through the relocalization of mitochondrial cyt c to the cytoplasm where it interacts with Apaf-1 in forming apoptosomes and mediating caspase-9 activation. Although the presence of heme moiety of cyt c is essential for the latter function, cyt c's redox catalytic features are not required. Lately, two other essential functions of cyt c in apoptosis, that may rely heavily on its redox activity have been suggested. Both functions are directed toward oxidation of two negatively charged phospholipids, cardiolipin (CL) in the mitochondria and phosphatidylserine (PS) in the plasma membrane. In both cases, oxidized phospholipids seem to be essential for the transduction of two distinctive apoptotic signals: one is participation of oxidized CL in the formation of the mitochondrial permeability transition pore that facilitates release of cyt c into the cytosol and the other is the contribution of oxidized PS to the externalization and recognition of PS (and possibly oxidized PS) on the cell surface by specialized receptors of phagocytes. In this review, we present a new concept that cyt c actuates both of these oxidative roles through a uniform mechanism: its specific interactions with each of these phospholipids result in the conversion and activation of cyt c, transforming it from an innocuous electron transporter into a calamitous peroxidase capable of oxidizing the activating phospholipids. We also show that this new concept is compatible with a leading role for reactive oxygen species in the execution of the apoptotic program, with cyt c as the main executioner.
Collapse
Affiliation(s)
- Valerian E Kagan
- Center for Free Radical and Antioxidant Health, Department of Environmental and Occupational Health, Pittsburgh, PA 15260, USA.
| | | | | | | | | | | | | | | | | |
Collapse
|
11
|
Ronquist G, Waldenström A. Imbalance of plasma membrane ion leak and pump relationship as a new aetiological basis of certain disease states. J Intern Med 2003; 254:517-26. [PMID: 14641792 DOI: 10.1111/j.1365-2796.2003.01235.x] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The basis for life is the ability of the cell to maintain ion gradients across biological membranes. Such gradients are created by specific membrane-bound ion pumps [adenosine triphosphatases (ATPases)]. According to physicochemical rules passive forces equilibrate (dissipate) ion gradients. The cholesterol/phospholipid ratio of the membrane and the degree of saturation of phospholipid fatty acids are important factors for membrane molecular order and herewith a determinant of the degree of non-specific membrane leakiness. Other operative principles, i.e. specific ion channels can be opened and closed according to mechanisms that are specific to the cell. Certain compounds called ionophores can be integrated in the plasma membrane and permit specific inorganic ions to pass. Irrespective of which mechanism ions leak across the plasma membrane the homeostasis may be kept by increasing ion pumping (ATPase activity) in an attempt to restore the physiological ion gradient. The energy source for this work seems to be glycolytically derived ATP formation. Thus an increase in ion pumping is reflected by increased ATP hydrolysis and rate of glycolysis. This can be measured as an accumulation of breakdown products of ATP and end-products of anaerobic glycolysis (lactate). In certain disease entities, the balance between ATP formation and ion pumping may be disordered resulting in a decrease in inter alia (i.a.) cellular energy charge, and an increase in lactate formation and catabolites of adenylates. Cardiac syndrome X is proposed to be due to an excessive leakage of potassium ions, leading to electrocardiographic (ECG) changes, abnormal Tl-scintigraphy of the heart and anginal pain (induced by adenosine). Cocksackie B3 infections, a common agent in myocarditis might also induce an ionophore-like effect. Moreover, Alzheimer's disease is characterized by the formation of extracellular amyloid deposits in the brain of patients. Perturbation of cellular membranes by the amyloid peptide during the development of Alzheimer's disease is one of several mechanisms proposed to account for the toxicity of this peptide on neuronal membranes. We have studied the effects of the peptide and fragments thereof on 45Ca2+-uptake in human erythrocytes and the energetic consequences. Treatment of erythrocytes with the beta 1-40 peptide, results in qualitatively similar nucleotide pattern and decrease of energy charge as the treatment with Ca2+-ionophore A23187. Finally, in recent studies we have revealed and published in this journal that a rare condition, Tarui's disease or glycogenosis type VII, primarily associated with a defect M-subunit of phosphofructokinase, demonstrates as a cophenomenon an increased leak of Ca2+ into erythrocytes.
Collapse
Affiliation(s)
- G Ronquist
- Department of Clinical Chemistry, University Hospital, Uppsala, Sweden.
| | | |
Collapse
|
12
|
Williamson P, Schlegel RA. Transbilayer phospholipid movement and the clearance of apoptotic cells. BIOCHIMICA ET BIOPHYSICA ACTA 2002; 1585:53-63. [PMID: 12531537 DOI: 10.1016/s1388-1981(02)00324-4] [Citation(s) in RCA: 145] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
When lymphocytes (and other cells) die by apoptosis, they orchestrate their own orderly removal by macrophages, and thereby prevent the inflammation that would otherwise attend cell lysis. As part of their demise, apoptotic cells disrupt the normal asymmetric distribution of phospholipids across their plasma membranes, an asymmetry normally maintained by an aminophospholipid translocase. This disruption of asymmetry, mediated by an activity known as the scramblase, generates ligands on the cell surface that trigger phagocytosis of the dying cell before lysis can occur. This crucial alteration of the plasma membrane is not dependent on caspase-mediated proteolysis, but quite unexpectedly, it is required both on the apoptotic target cell and on the phagocyte that engulfs it. At least in the phagocyte, this rearrangement may depend on the activity of an ABC ATPase, termed ABC1 in mammals and ced-7 in C. elegans.
Collapse
|
13
|
Abstract
Most biological membranes possess an asymmetric transbilayer distribution of phospholipids. Endogenous enzymes expend energy to maintain the arrangement by promoting the rate of phospholipid translocation, or flip-flop. Researchers have discovered ways to modify this distribution through the use of chemicals. This review presents a critical analysis of the phospholipid asymmetry data in the literature followed by a brief overview of the maintenance and physiological consequences of phospholipid asymmetry, and finishes with a list of chemical ways to alter phospholipid distribution by enhancement of flip-flop.
Collapse
Affiliation(s)
- J Middleton Boon
- Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556-5670, USA
| | | |
Collapse
|
14
|
Affiliation(s)
- Peter J Quinn
- Division of Life Sciences, King's College London, 150 Stamford Street, London SE1 9NN, UK
| |
Collapse
|
15
|
Ding J, Wu Z, Crider BP, Ma Y, Li X, Slaughter C, Gong L, Xie XS. Identification and functional expression of four isoforms of ATPase II, the putative aminophospholipid translocase. Effect of isoform variation on the ATPase activity and phospholipid specificity. J Biol Chem 2000; 275:23378-86. [PMID: 10801890 DOI: 10.1074/jbc.m910319199] [Citation(s) in RCA: 91] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
ATPase II, a vanadate-sensitive and phosphatidylserine-dependent Mg(2+)-ATPase, is a member of a subfamily of P-type ATPase and is presumably responsible for aminophospholipid translocation activity in eukaryotic cells. The aminophospholipid translocation activity plays an important physiological role in the maintenance of membrane phospholipid asymmetry that is observed in the plasma membrane as well as the membranes of certain cellular organelles. While the preparations of ATPase II from different sources share common fundamental properties, such as substrate specificity, inhibitor spectrum, and phospholipid dependence, they are divergent in several characteristics. These include specific ATPase activity and phospholipid selectivity. We report here the identification of four isoforms of ATPase II in bovine brain. These isoforms are formed by a combination of two major variations in their primary sequences and show that the structural variation of these isoforms has functional significance in both ATPase activity and phosholipid selectivity. Furthermore, studies with the phosphoenzyme intermediate of ATPase II and its recombinant isoforms revealed that phosphatidylserine is essential for the dephosphorylation of the intermediate. Without phosphatidylserine, ATPase II would be accumulated as phosphoenzyme in the presence of ATP, resulting in the interruption of its catalytic cycle.
Collapse
Affiliation(s)
- J Ding
- Division of Molecular Transport, Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas, Texas 75235-9121, USA
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Daleke DL, Lyles JV. Identification and purification of aminophospholipid flippases. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1486:108-27. [PMID: 10856717 DOI: 10.1016/s1388-1981(00)00052-4] [Citation(s) in RCA: 152] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Transbilayer phospholipid asymmetry is a common structural feature of most biological membranes. This organization of lipids is generated and maintained by a number of phospholipid transporters that vary in lipid specificity, energy requirements and direction of transport. These transporters can be divided into three classes: (1) bidirectional, non-energy dependent 'scramblases', and energy-dependent transporters that move lipids (2) toward ('flippases') or (3) away from ('floppases') the cytofacial surface of the membrane. One of the more elusive members of this family is the plasma membrane aminophospholipid flippase, which selectively transports phosphatidylserine from the external to the cytofacial monolayer of the plasma membrane. This review summarizes the characteristics of aminophospholipid flippase activity in intact cells and describes current strategies to identify and isolate this protein. The biochemical characteristics of candidate flippases are critically compared and their potential role in flippase activity is evaluated.
Collapse
Affiliation(s)
- D L Daleke
- Department of Biochemistry and Molecular Biology and Medical Sciences Program, Indiana University, Bloomington 47405, USA.
| | | |
Collapse
|
17
|
Chen CY, Ingram MF, Rosal PH, Graham TR. Role for Drs2p, a P-type ATPase and potential aminophospholipid translocase, in yeast late Golgi function. J Cell Biol 1999; 147:1223-36. [PMID: 10601336 PMCID: PMC2168089 DOI: 10.1083/jcb.147.6.1223] [Citation(s) in RCA: 205] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/1999] [Accepted: 11/09/1999] [Indexed: 11/22/2022] Open
Abstract
ADP-ribosylation factor appears to regulate the budding of both COPI and clathrin-coated transport vesicles from Golgi membranes. An arf1Delta synthetic lethal screen identified SWA3/DRS2, which encodes an integral membrane P-type ATPase and potential aminophospholipid translocase (or flippase). The drs2 null allele is also synthetically lethal with clathrin heavy chain (chc1) temperature-sensitive alleles, but not with mutations in COPI subunits or other SEC genes tested. Consistent with these genetic analyses, we found that the drs2Delta mutant exhibits late Golgi defects that may result from a loss of clathrin function at this compartment. These include a defect in the Kex2-dependent processing of pro-alpha-factor and the accumulation of abnormal Golgi cisternae. Moreover, we observed a marked reduction in clathrin-coated vesicles that can be isolated from the drs2Delta cells. Subcellular fractionation and immunofluorescence analysis indicate that Drs2p localizes to late Golgi membranes containing Kex2p. These observations indicate a novel role for a P-type ATPase in late Golgi function and suggest a possible link between membrane asymmetry and clathrin function at the Golgi complex.
Collapse
Affiliation(s)
- Chih-Ying Chen
- Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37235
| | - Michael F. Ingram
- Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37235
| | - Peter H. Rosal
- Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37235
| | - Todd R. Graham
- Department of Molecular Biology, Vanderbilt University, Nashville, Tennessee 37235
| |
Collapse
|
18
|
Tang X, Halleck MS, Schlegel RA, Williamson P. A subfamily of P-type ATPases with aminophospholipid transporting activity. Science 1996; 272:1495-7. [PMID: 8633245 DOI: 10.1126/science.272.5267.1495] [Citation(s) in RCA: 352] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The appearance of phosphatidylserine on the surface of animal cells triggers phagocytosis and blood coagulation. Normally, phosphatidylserine is confined to the inner leaflet of the plasma membrane by an aminophospholipid translocase, which has now been cloned and sequenced. The bovine enzyme is a member of a previously unrecognized subfamily of P-type adenosine triphosphatases (ATPases) that may have diverged from the primordial enzyme before the separation of the known families of ion-translocating ATPases. Studies in Saccharomyces cerevisiae suggest that aminophospholipid translocation is a general function of members of this family.
Collapse
Affiliation(s)
- X Tang
- Department of Biology, Amherst College, MA 01002, USA
| | | | | | | |
Collapse
|
19
|
Nucleotide Labeling and Reconstitution of the Recombinant 58-kDa Subunit of the Vacuolar Proton-translocating ATPase. J Biol Chem 1995. [DOI: 10.1016/s0021-9258(17)46929-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
|
20
|
|
21
|
Williamson P, Schlegel RA. Back and forth: the regulation and function of transbilayer phospholipid movement in eukaryotic cells. Mol Membr Biol 1994; 11:199-216. [PMID: 7711830 DOI: 10.3109/09687689409160430] [Citation(s) in RCA: 164] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
That some membranes restrict certain lipid species to one side of the bilayer and others to the opposite side has been known for two decades. However, how this asymmetric transbilayer distribution is generated and controlled, how many and what type of membranes are so structured, and even the reason for its existence is just now beginning to be understood. It has been a decade since the discovery of an activity which transports in an ATP-dependent manner only the aminophospholipids from the outer to the inner leaflet of the plasma membrane. This aminophospholipid translocase has yet to be isolated, reconstituted, and identified molecularly. Elevating intracellular Ca2+ allows all the major classes of phospholipids to move freely across the bilayer, scrambling lipids and dissipating asymmetry. The nature of this pathway and its mode of activation by Ca2+ remain to be determined. Though loss of transbilayer asymmetry by blood cells clearly produces a procoagulant surface and increases interactions with the reticuloendothelial system, it remains to be elucidated whether maintenance of blood homeostasis is just one expression of a more general raison d'être for lipid asymmetry. It is these persisting uncertainties and gaps in our knowledge which make the field such an interesting and exciting challenge at the present time.
Collapse
Affiliation(s)
- P Williamson
- Department of Biology, Amherst College, MA 01002
| | | |
Collapse
|
22
|
Parsons SM, Prior C, Marshall IG. Acetylcholine transport, storage, and release. INTERNATIONAL REVIEW OF NEUROBIOLOGY 1993; 35:279-390. [PMID: 8463062 DOI: 10.1016/s0074-7742(08)60572-3] [Citation(s) in RCA: 163] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
ACh is released from cholinergic nerve terminals under both resting and stimulated conditions. Stimulated release is mediated by exocytosis of synaptic vesicle contents. The structure and function of cholinergic vesicles are becoming known. The concentration of ACh in vesicles is about 100-fold greater than the concentration in the cytoplasm. The AChT exhibits the lowest binding specificity among known ACh-binding proteins. It is driven by efflux of protons pumped into the vesicle by the V-type ATPase. A potent pharmacology of the AChT based on the allosteric VR has been developed. It has promise for clinical applications that include in vivo evaluation of the density of cholinergic innervation in organs based on PET and SPECT. The microscopic kinetics model that has been developed and the very low transport specificity of the vesicular AChT-VR suggest that the transporter has a channel-like or multidrug resistance protein-like structure. The AChT-VR has been shown to be tightly associated with proteoglycan, which is an unexpected macromolecular relationship. Vesamicol and its analogs block evoked release of ACh from cholinergic nerve terminals after a lag period that depends on the rate of release. Recycling quanta of ACh that are sensitive to vesamicol have been identified electrophysiologically, and they constitute a functional correlate of the biochemically identified VP2 synaptic vesicles. The concept of transmitter mobilization, including the observation that the most recently synthesized ACh is the first to be released, has been greatly clarified because of the availability of vesamicol. Differences among different cholinergic nerve terminal types in the sensitivity to vesamicol, the relative amounts of readily and less releasable ACh, and other aspects of the intracellular metabolism of ACh probably are more apparent than real. They easily could arise from differences in the relative rates of competing or sequential steps in the complicated intraterminal metabolism of ACh rather than from fundamental differences among the terminals. Nonquantal release of ACh from motor nerve terminals arises at least in part from the movement of cytoplasmic ACh through the AChT located in the cytoplasmic membrane, and it is blocked by vesamicol. Possibly, the proteoglycan component of the AChT-VR produces long-term residence of the macromolecular complex in the cytoplasmic membrane through interaction with the synaptic matrix. The preponderance of evidence suggests that a significant fraction of what previously, heretofore, had been considered to be nonquantal release from the motor neuron actually is quantal release from the neuron at sites not detected electrophysiologically.(ABSTRACT TRUNCATED AT 400 WORDS)
Collapse
Affiliation(s)
- S M Parsons
- Department of Chemistry, University of California, Santa Barbara 93106
| | | | | |
Collapse
|
23
|
Hicks BW, Parsons SM. Characterization of the P-type and V-type ATPases of cholinergic synaptic vesicles and coupling of nucleotide hydrolysis to acetylcholine transport. J Neurochem 1992; 58:1211-20. [PMID: 1312570 DOI: 10.1111/j.1471-4159.1992.tb11331.x] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Both phosphointermediate- and vacuolar-type (P- and V-type, respectively) ATPase activities found in cholinergic synaptic vesicles isolated from electric organ are immunoprecipitated by a monoclonal antibody to the SV2 epitope characteristic of synaptic vesicles. The two activities can be distinguished by assay in the absence and presence of vanadate, an inhibitor of the P-type ATPase. Each ATPase has two overlapping activity maxima between pH 5.5 and 9.5 and is inhibited by fluoride and fluorescein isothiocyanate. The P-type ATPase hydrolyzes ATP and dATP best among common nucleotides, and activity is supported well by Mg2+, Mn2+, or Co2+ but not by Ca2+, Cd2+, or Zn2+. It is stimulated by hyposmotic lysis, detergent solubilization, and some mitochondrial uncouplers. Kinetic analysis revealed two Michaelis constants for MgATP of 28 microM and 3.1 mM, and the native enzyme is proposed to be a dimer of 110-kDa subunits. The V-type ATPase hydrolyzes all common nucleoside triphosphates, and Mg2+, Ca2+, Cd2+, Mn2+, and Zn2+ all support activity effectively. Active transport of acetylcholine (ACh) also is supported by various nucleoside triphosphates in the presence of Ca2+ or Mg2+, and the Km for MgATP is 170 microM. The V-type ATPase is stimulated by mitochondrial uncouplers, but only at concentrations significantly above those required to inhibit ACh active uptake. Kinetic analysis of the V-type ATPase revealed two Michaelis constants for MgATP of approximately 26 microM and 2.0 mM. The V-type ATPase and ACh active transport were inhibited by 84 and 160 pmol of bafilomycin A1/mg of vesicle protein, respectively, from which it is estimated that only one or two V-type ATPase proton pumps are present per synaptic vesicle. The presence of presumably contaminating Na+,K(+)-ATPase in the synaptic vesicle preparation is demonstrated.
Collapse
Affiliation(s)
- B W Hicks
- Department of Chemistry, University of California, Santa Barbara 93106
| | | |
Collapse
|
24
|
Verhoven B, Schlegel RA, Williamson P. Rapid loss and restoration of lipid asymmetry by different pathways in resealed erythrocyte ghosts. BIOCHIMICA ET BIOPHYSICA ACTA 1992; 1104:15-23. [PMID: 1550843 DOI: 10.1016/0005-2736(92)90126-7] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The normal asymmetric distribution of phospholipids across the plasma membrane of erythrocytes can be abolished by lysing and resealing cells in the presence of Ca2+. In the present study, using flow cytometric analysis of the binding of merocyanine 540 to monitor transbilayer phospholipid distribution, Ca(2+)-induced loss of asymmetry is shown to be independent from the aminophospholipid translocase which catalyzes movement of normally internal phospholipids from the outer to the inner leaflet of the membrane. Loss of asymmetry is rapid, temperature-sensitive, and occurs in an uninterrupted, intact bilayer, rather than by diffusion of lipids through the hemolytic pore. Addition of ATP during lysis reverses loss of asymmetry, and this restoration can be blocked by inhibitors of the aminophospholipid translocase. These results suggest that the ATP-dependent translocase is essential for recovery of asymmetry, in turn suggesting that separate mechanisms mediate the loss and the recovery of lipid asymmetry in erythrocytes.
Collapse
Affiliation(s)
- B Verhoven
- Department of Biology, Amherst College, MA 01002
| | | | | |
Collapse
|
25
|
Moriyama Y, Nelson N, Maeda M, Futai M. Vanadate-sensitive ATPase from chromaffin granule membranes formed a phosphoenzyme intermediate and was activated by phosphatidylserine. Arch Biochem Biophys 1991; 286:252-6. [PMID: 1832831 DOI: 10.1016/0003-9861(91)90037-j] [Citation(s) in RCA: 28] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Vanadate-sensitive ATPase (115 kDa molecular weight) in adrenal chromaffin granules is an intrinsic membrane enzyme with its catalytic site located at the outer surface of the granules. Upon incubation with [gamma-32P]ATP, the purified ATPase formed an alkaline-labile phosphoenzyme intermediate, which was inhibited by vanadate but not by Na+ or K+. Ratio of ATPase or phosphatase activity and formation of phosphoenzyme intermediate was constant during purification after the first glycerol density gradient centrifugation. Phosphatidylserine specifically activated the enzyme about three-fold by increasing the Vmax value without changing the Km for ATP. Other phospholipids, including phosphatidylglycerol, phosphatidylcholine, phosphatidylinositol, and phosphatidylethanolamine, as well as lysophospholipids and detergents, had no effect. These results indicated that the vanadate-sensitive ATPase belongs to the P-type ATPases, which differ from known cation-translocating P-type ATPases.
Collapse
Affiliation(s)
- Y Moriyama
- Department of Organic Chemistry and Biochemistry, Osaka University, Japan
| | | | | | | |
Collapse
|
26
|
Perin MS, Fried VA, Stone DK, Xie XS, Südhof TC. Structure of the 116-kDa polypeptide of the clathrin-coated vesicle/synaptic vesicle proton pump. J Biol Chem 1991. [DOI: 10.1016/s0021-9258(19)67875-0] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
27
|
Floor E, Leventhal PS, Schaeffer SF. Partial purification and characterization of the vacuolar H(+)-ATPase of mammalian synaptic vesicles. J Neurochem 1990; 55:1663-70. [PMID: 2145397 DOI: 10.1111/j.1471-4159.1990.tb04954.x] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Several major proteins of synaptic vesicles from rat or cow brain sediment as a large complex on sucrose density gradients when solubilized in nonionic detergents. A vacuolar H(+)-ATPase identified by sensitivity to bafilomycin A1 appears to be associated with this oligomeric protein complex. Two subunits of this complex, synaptic vesicle proteins S and U, correspond to the 57-kDa (B) and 39-kDa accessory (Ac39) subunits, respectively, of bovine chromaffin granule vacuolar H(+)-ATPase as shown by Western immunoblot analysis. The five subunits of the oligomeric complex constitute approximately 20% of the total protein of rat brain synaptic vesicles. Taken together, these results strongly suggest that the abundant, multisubunit complex partially purified from brain synaptic vesicles by density gradient centrifugation is a vacuolar H(+)-ATPase. Bafilomycin A1 completely blocks proton pumping in rat brain synaptic vesicles as measured by [14C]methylamine uptake and also blocks catecholamine accumulation measured by [3H]dopamine uptake. Moreover, ATPase activity, [14C]methylamine uptake, and [3H]dopamine uptake are inhibited by bafilomycin A1 at similar I50 values of approximately 1.7 nmol/mg of protein. These findings indicate that the vacuolar H(+)-ATPase is essential for proton pumping as well as catecholamine uptake by mammalian synaptic vesicles.
Collapse
Affiliation(s)
- E Floor
- Department of Anatomy, University of Wisconsin Medical School, Madison
| | | | | |
Collapse
|
28
|
Morrot G, Zachowski A, Devaux PF. Partial purification and characterization of the human erythrocyte Mg2(+)-ATPase. A candidate aminophospholipid translocase. FEBS Lett 1990; 266:29-32. [PMID: 2142104 DOI: 10.1016/0014-5793(90)81498-d] [Citation(s) in RCA: 85] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A Mg2(+)-ATPase-enriched fraction was obtained from solubilized human erythrocyte membranes by ammonium sulphate precipitation and anion-exchange chromatography. The solubilized enzyme, of apparent molecular weight 120 kDa, requires phosphatidylserine to be fully active. Phosphatidylethanolamine but not other anionic phospholipids can only partially restore the activity. The Mg-ATPase has a low affinity for Mg2(+)-ATP and is inhibited by fluoride, vanadate, vanadyl and calcium ions. From these characteristics, we infer that this Mg2(+)-ATPase is the same protein as the aminophospholipid translocase which regulates the membrane phospholipid transverse distribution in human erythrocytes by actively transporting aminophospholipids from the outer to the inner monolayer.
Collapse
Affiliation(s)
- G Morrot
- Institut de Biologie Physico-Chimique, Paris, France
| | | | | |
Collapse
|
29
|
Bekker PJ, Gay CV. Biochemical characterization of an electrogenic vacuolar proton pump in purified chicken osteoclast plasma membrane vesicles. J Bone Miner Res 1990; 5:569-79. [PMID: 2166421 DOI: 10.1002/jbmr.5650050606] [Citation(s) in RCA: 64] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
A well-characterized chicken osteoclast plasma membrane vesicle preparation manifested Mg2(+)-dependent ATP hydrolyzing activity of 0.213 mumol inorganic phosphate released per mg protein per minute (n = 7). The Mg2+ dependence showed a high-affinity component with a KMg of 1.293 microM and Vmax of 0.063 mumol Pi per mg protein per minute, and a low-affinity component with a KMg of 297.6 microM and a Vmax of 0.232 mumol Pi per mg protein per minute. The Mg2(+)-ATPase activity was inhibited by N,N'-dicyclohexylcarbodiimide (DCCD, 0.2 mM, 50.7%), N-ethylmaleimide (0.5 mM, 34.6%), nolinium bromide (1 mM, 29.9%), 4,4'-diisothiocyano-2,2'-stilbene sulfonic acid (DIDS, 1 mM, 45.1%), and p-chloromercuribenzoic acid (PCMB, 0.1 mM, 33.8%). Sodium orthovanadate (Na3 VO4) at 1 microM had no effect but caused 29.5% inhibition at 1 mM. Na+ could substitute for K+ without loss of activity, NO3- caused 19.5% inhibition when substituted for Cl-, and acetate replacement of Cl- resulted in 36.4% stimulation of Mg2(+)-ATPase. ATP, GTP, ITP, CTP, and ADP were all hydrolyzed effectively. DCCD (0.2 mM), NEM (0.5 mM), nolinium bromide (1 mM), and DIDS (50 microM) almost completely abolished proton transport as measured spectrofluorometrically by acridine orange quenching. Na3 VO4 (1 mM) had no effect, and duramycin (80 micrograms/ml) inhibited transport 52.7%. K+ replacement of Na+ caused a 79.2% increase in initial proton transport rate. NO3- and acetate substitution of Cl- resulted in a 46.1 and 55.7% decrease in transport, respectively. ATP supports transport far more effectively than the other nucleotides tested. ADP was ineffective. Experiments using the potassium ionophore, valinomycin, indicated that the proton pump functions electrogenically, with Cl- most likely cotransported by an anion transporter. The proton pump also seems to have at least one anion-sensitive site, elucidated by experiments in the presence of NO3- and Cl-.
Collapse
Affiliation(s)
- P J Bekker
- Department of Molecular and Cell Biology, Pennsylvania State University, University Park 16802
| | | |
Collapse
|
30
|
Kindberg GM, Gudmundsen O, Berg T. The effect of vanadate on receptor-mediated endocytosis of asialoorosomucoid in rat liver parenchymal cells. J Biol Chem 1990. [DOI: 10.1016/s0021-9258(19)38802-7] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
|
31
|
Abstract
Fifty to eighty-five percent of the ATPase activity in different preparations of cholinergic synaptic vesicles isolated from Torpedo electric organ was half-inhibited by 7 microM vanadate. This activity is due to a recently purified phosphointermediate, or P-type, ATPase, Acetylcholine (ACh) active transport by the vesicles was stimulated about 35% by vanadate, demonstrating that the P-type enzyme is not the proton pump responsible for ACh active transport. Nearly all of the vesicle ATPase activity was inhibited by N-ethylmaleimide. The P-type ATPase could be protected from N-ethylmaleimide inactivation by vanadate, and subsequently reactivated by complexation of vanadate with deferoxamine. The inactivation-protection pattern suggests the presence of a vanadate-insensitive, N-ethylmaleimide-sensitive ATPase consistent with a vacuolar, or V-type, activity expected to drive ACh active transport. ACh active transport was half-inhibited by 5 microM N-ethylmaleimide, even in the presence of vanadate. The presence of a V-type ATPase was confirmed by Western blots using antisera raised against three separate subunits of chromaffin granule vacuolar ATPase I. Both ATPase activities, the P-type polypeptides, and the 38-kilodalton polypeptide of the V-type ATPase precisely copurify with the synaptic vesicles. Solubilization of synaptic vesicles in octaethyleneglycol dodecyl ether detergent results in several-fold stimulation of the P-type activity and inactivation of the V-type activity, thus explaining why the V-type activity was not detected previously during purification of the P-type ATPase. It is concluded that cholinergic vesicles contain a P-type ATPase of unknown function and a V-type ATPase which is the proton pump.
Collapse
Affiliation(s)
- S K Yamagata
- Department of Chemistry, IES, University of California, Santa Barbara 93106
| | | |
Collapse
|
32
|
Yamagata SK, Noremberg K, Parsons SM. Purification and subunit composition of a cholinergic synaptic vesicle glycoprotein, phosphointermediate-forming ATPase. J Neurochem 1989; 53:1345-53. [PMID: 2529350 DOI: 10.1111/j.1471-4159.1989.tb08524.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
A glycoprotein ATPase in cholinergic synaptic vesicles of Torpedo electric organ was solubilized with octa-ethylene glycol dodecyl ether detergent. Study of potential stabilizing factors identified crude brain phosphatidylserine, glycerol, dithiothreitol, and protease inhibitors as of value in maintaining activity. The ATPase was purified from the solubilized, stabilized material by glycerol density gradient band sedimentation velocity ultracentrifugation, and hydroxylapatite, wheat germ lectin affinity, and size exclusion chromatographies. The pure ATPase had a specific activity of about 37 mumol ATP hydrolyzed/min/mg protein. After sodium dodecyl sulfate-polyacrylamide gel electrophoresis, the purified material typically exhibited three polypeptides of molecular masses 110, 104, and 98 kilodaltons (kDa) and a fourth diffuse polypeptide of 60 kDa. This composition suggests that the ATPase is a member of the P-type, or phosphointermediate-forming, family, but it was shown to be distinct from the ouabain-sensitive Na+,K+- and CA2+-stimulated Mg2+-ATPases. The purified vesicle enzyme was rapidly phosphorylated by [gamma-32P]ATP on about 14% of the subunits with molecular weights of 98,000-110,000. About 16% of the ATPase was phosphorylated in whole-vesicle ghosts in a manner consistent with formation of a phosphointermediate, thus confirming the P-type nature of this enzyme.
Collapse
Affiliation(s)
- S K Yamagata
- Department of Chemistry, University of California, Santa Barbara 93106
| | | | | |
Collapse
|
33
|
Abstract
Recently a new class of proton-translocating ATPases has been localized to endomembrane compartments in plant, fungal, and mammalian cells. These proton pumps are large hetero-oligomers which have an ATP hydrolytic sector that is functionally and structurally distinct from a transmembranous proton pore. Enzymatic characteristics of these proton pumps are discussed as well as the current state of knowledge regarding subunit composition and function. In addition, recent primary sequence data are discussed which indicate that these proton pumps share a common ancestor with F1F0-type proton pumps of mitochondria.
Collapse
Affiliation(s)
- D K Stone
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas 75235
| | | | | | | |
Collapse
|