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Structure-Function Relationship of the SERCA Pump and Its Regulation by Phospholamban and Sarcolipin. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2017; 981:77-119. [DOI: 10.1007/978-3-319-55858-5_5] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
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Becucci L, Foresti ML, Schwan A, Guidelli R. Can proton pumping by SERCA enhance the regulatory role of phospholamban and sarcolipin? BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1828:2682-90. [DOI: 10.1016/j.bbamem.2013.07.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Revised: 06/22/2013] [Accepted: 07/08/2013] [Indexed: 11/26/2022]
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Becucci L, Guidelli R, Karim CB, Thomas DD, Veglia G. The role of sarcolipin and ATP in the transport of phosphate ion into the sarcoplasmic reticulum. Biophys J 2010; 97:2693-9. [PMID: 19917222 DOI: 10.1016/j.bpj.2009.08.035] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2009] [Revised: 08/01/2009] [Accepted: 08/25/2009] [Indexed: 10/20/2022] Open
Abstract
In a previous study, sarcolipin (SLN) was shown to form channels selective toward chloride ion when incorporated in a mercury-supported tethered bilayer lipid membrane (tBLM). Its incorporation had only a modest permeabilizing effect on phosphate ion. In this note the resistance of a tBLM membrane incorporating sarcolipin was investigated by electrochemical impedance spectroscopy in aqueous solutions of 0.05 M sodium phosphate of pH ranging from 5.3 to 8, in the presence of ATP, adenosine monophosphate, and phenylphosphonic acid. At pH 5.3, submicromolar additions of ATP increase the conductivity of the tBLM incorporating SLN up to a maximum limiting value. The dependence of the conductivity on the ATP concentration satisfies the Michaelis-Menten equation, with an association constant of 0.1 microM. Phenylphosphonium ion and adenosine monophosphate exert an inhibitory effect on membrane permeabilization to phosphate ions by ATP if they are added before ATP, but not if they are added after it. An explanation for this behavior is provided. In conclusion, SLN acts as an ATP-induced phosphate carrier exhibiting a behavior quite similar to that of the unidentified P(i) transporter described previously. No ion-channel activity is exhibited by the T18A mutant of SLN.
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Affiliation(s)
- Lucia Becucci
- Chemistry Department, Florence University, Florence, Italy
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Becucci L, Guidelli R, Karim CB, Thomas DD, Veglia G. An electrochemical investigation of sarcolipin reconstituted into a mercury-supported lipid bilayer. Biophys J 2007; 93:2678-87. [PMID: 17586575 PMCID: PMC1989701 DOI: 10.1529/biophysj.107.109280] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sarcolipin was incorporated into a lipid bilayer anchored to a mercury electrode through a hydrophilic tetraethyleneoxy chain. The behavior of this tethered bilayer lipid membrane incorporating sarcolipin was investigated by electrochemical impedance spectroscopy and by recording charge versus time curves after potential jumps. When the transmembrane potential starts to become negative on the trans side, evidence is provided that sarcolipin aggregates into ion-conducting pores. Over the range of physiological transmembrane potentials, these pores are permeable to small inorganic anions such as chloride, phosphate, or sulfate but impermeable to inorganic cations such as Na+ and K+. Only at transmembrane potentials more negative than approximately -150 mV on the trans side do sarcolipin channels allow the translocation of the latter cations. A tentative relationship between this property of sarcolipin and its regulatory function on Ca-ATPase of sarcoplasmic reticulum is proposed.
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Affiliation(s)
- Lucia Becucci
- Chemistry Department, Florence University, 50019 Florence, Italy
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Csala M, Marcolongo P, Lizák B, Senesi S, Margittai E, Fulceri R, Magyar JE, Benedetti A, Bánhegyi G. Transport and transporters in the endoplasmic reticulum. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2007; 1768:1325-41. [PMID: 17466261 DOI: 10.1016/j.bbamem.2007.03.009] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2006] [Revised: 03/08/2007] [Accepted: 03/15/2007] [Indexed: 12/12/2022]
Abstract
Enzyme activities localized in the luminal compartment of the endoplasmic reticulum are integrated into the cellular metabolism by transmembrane fluxes of their substrates, products and/or cofactors. Most compounds involved are bulky, polar or even charged; hence, they cannot be expected to diffuse through lipid bilayers. Accordingly, transport processes investigated so far have been found protein-mediated. The selective and often rate-limiting transport processes greatly influence the activity, kinetic features and substrate specificity of the corresponding luminal enzymes. Therefore, the phenomenological characterization of endoplasmic reticulum transport contributes largely to the understanding of the metabolic functions of this organelle. Attempts to identify the transporter proteins have only been successful in a few cases, but recent development in molecular biology promises a better progress in this field.
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Affiliation(s)
- Miklós Csala
- Department of Medical Chemistry, Molecular Biology and Pathobiochemistry, Semmelweis University, Budapest, Hungary
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Acharya A. N(2)O(2)-induced apoptosis of thymocytes involves mobilization of divalent cations. Int J Immunopathol Pharmacol 2002; 15:195-200. [PMID: 12575919 DOI: 10.1177/039463200201500305] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
More than 90% of thymocytes undergo apoptosis while undergoing differentiation in the thymus. Although several factors act in concert to induce thymocyte apoptosis, it remains speculative if reactive oxygen intermediates produced by thymic macrophages may play a role in this process. The present investigation was carried out to determine if H(2)O(2) is capable of inducing apoptosis of thymocytes in vitro. It was observed that H(2)O(2) could induce apoptosis of thymocytes in vitro in a dose and time dependent manner. It was further found that H(2)O(2)-induced thymocyte apoptosis was dependent on the mobilization of divalent cations. The result of this study will help further in the understanding of the mechanism of H(2)O(2)-induced apoptosis
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Affiliation(s)
- A. Acharya
- Dept. Zoology, Faculty of Science, Banaras Hindu University, Varanasi, India
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Dulhunty AF, Lavert DR. A Ca2+-activated anion channel in the sarcoplasmic reticulum of skeletal muscle. CURRENT TOPICS IN MEMBRANES 2002. [DOI: 10.1016/s1063-5823(02)53028-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Abstract
1. Phosphate ions (P(i)) enter intracellular Ca2+ stores and precipitate Ca2+. Since transport pathways for P(i) across the membrane of intracellular calcium stores have not been identified and anion channels could provide such a pathway, we have examined the P(i) conductance of single anion channels from the sarcoplasmic reticulum (SR) of rabbit skeletal muscle using the lipid bilayer technique. 2. Two anion channels in skeletal muscle SR, the small conductance (SCl) and big conductance (BCl) chloride channels, were both found to have a P(i) conductance of 10 pS in 50 mM P(i). The SCl channel is a divalent anion channel which can pass HPO4(2-) as well as SO4(2-) (60 pS in 100 mM free SO4(2-)). The BCl channel is primarily a monovalent anion channel. The SCl and BCl channels are permeable to a number of small monovalent anions, showing minor selectivity between Cl-, I- and Br- (Cl- > I- > Br-) and relative impermeability to cations and large polyatomic anions (Cs+, Na+, choline+, Tris+, Hepes- and CH3O3S-). 3. The P(i) conductance of SCl and BCl channels suggests that both channel types could sustain the observed P(i) fluxes across the SR membrane. Comparison of the blocking effects of the phosphonocarboxylic acids, ATP and DIDS, on the anion channels with their effects on P(i) transport suggests that the SCl channel is the more likely candidate for the SR P(i) transport mechanism. 4. The SCl channel, with previously unknown function, provides a regulated pathway for P(i) across the SR membrane which would promote P(i) entry and thereby changes in the rapidly releasable Ca2+ store during onset and recovery from muscle fatigue. Anion channels may provide a pathway for P(i) movement into and out of Ca2+ stores in general.
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Affiliation(s)
- D R Laver
- School of Biochemistry and Molecular Biology, Faculty of Science, Australian National University, Canberra, ACT 0200, Australia.
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Posterino GS, Fryer MW. Mechanisms underlying phosphate-induced failure of Ca2+ release in single skinned skeletal muscle fibres of the rat. J Physiol 1998; 512 ( Pt 1):97-108. [PMID: 9729620 PMCID: PMC2231177 DOI: 10.1111/j.1469-7793.1998.097bf.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
1. Single mechanically skinned fibres from rat extensor digitorum longus (EDL) muscles were used to investigate the mechanisms underlying inorganic phosphate (Pi) movements between the myoplasm and the sarcoplasmic reticulum (SR). Force transients elicited by caffeine/low Mg2+ application were used to assess the rate of Pi-induced inhibition of SR Ca2+ release and the subsequent recovery of Ca2+ release following removal of myoplasmic Pi. 2. Myoplasmic Pi reduced SR Ca2+ release in a concentration- and time-dependent manner. A 10 s exposure to 10, 20 and 50 mM myoplasmic Pi reduced SR Ca2+ release by 12 +/- 9, 29 +/- 5 and 82 +/- 5 %, respectively. 3. Removal of myoplasmic ATP at the time of Pi exposure significantly increased the rate and extent of SR Ca2+ release inhibition. For example, Ca2+ release was reduced by 86 +/- 6 % (n = 6) after 20 s exposure to 20 mM Pi in the absence of ATP compared with only 47 +/- 5 % (n = 5) in the presence of ATP. 4. The half and full recovery times for SR Ca2+ release following washout of myoplasmic Pi were 35 s and approximately 7 min, respectively. Recovery of Ca2+ release was unaffected by the absence of ATP during washout of Pi but was prevented when fibres were washed in the presence of high myoplasmic Pi (30 mM). Neither the Pi transporter blocker phenylphosphonic acid (PHPA) nor the anion channel blockers anthracene-9-carboxylic acid (9-AC) and 4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid (DIDS) affected the rate of recovery of SR Ca2+ release. 5. These results show that Pi entry and exit from the SR occur primarily through a passive pathway that is insensitive to well-known anion channel blockers. Pi inhibition of SR Ca2+ release appears to be a complicated phenomenon influenced by the rate of Pi movement across the SR as well as by the rate, extent and species of Ca2+-Pi precipitate formation in the SR lumen. The more rapid inhibitory effect of Pi in the absence of myoplasmic ATP suggests that Pi may inhibit SR Ca2+ release more efficiently during the later stages of fatigue.
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Affiliation(s)
- G S Posterino
- School of Physiology and Pharmacology, The University of New South Wales, Sydney, New South Wales 2052, Australia
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Fryer MW, West JM, Stephenson DG. Phosphate transport into the sarcoplasmic reticulum of skinned fibres from rat skeletal muscle. J Muscle Res Cell Motil 1997; 18:161-7. [PMID: 9127264 DOI: 10.1023/a:1018605605757] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The rate, magnitude and pharmacology of inorganic phosphate (Pi) transport into the sarcoplasmic reticulum were estimated in single, mechanically skinned skeletal muscle fibres of the rat. This was done, indirectly, by using a technique that measured the total Ca2+ content of the sarcoplasmic reticulum and by taking advantage of the 1:1 stoichiometry of Ca2+ and Pi transport into the sarcoplasmic reticulum lumen during Ca-Pi precipitation-induced Ca2+ loading. The apparent rate of Pi entry into the sarcoplasmic reticulum increased with increasing myoplasmic [Pi] in the 10 mM-50 mM range at a fixed, resting myoplasmic pCa of 7.15, as judged by the increase in the rate of Ca-Pi precipitation-induced sarcoplasmic reticulum Ca2+ uptake. At 20 mM myoplasmic [Pi] the rate of Pi entry was calculated to be at least 51 microM s-1 while the amount of Pi loaded appeared to saturate at around 3.5 mM (per fibre volume). These values are approximations due to the complex kinetics of formation of different species of Ca-Pi precipitate formed under physiological conditions. Phenylphosphonic acid (PhPA, 2.5 mM) inhibited Pi transport by 37% at myoplasmic pCa 6.5 and also had a small, direct inhibitory effect on the sarcoplasmic reticulum Ca2+ pump (16%). In contrast, phosphonoformic acid (PFA, 1 mM) appeared to enhance both the degree of Pi entry and the activity of the sarcoplasmic reticulum Ca2+ pump, results that were attributed to transport of PFA into the sarcoplasmic reticulum lumen and its subsequent complexation with Ca2+. Thus, results from these studies indicate the presence of a Pi transporter in the sarcoplasmic reticulum membrane of mammalian skeletal muscle fibres that is (1) active at physiological concentrations of myoplasmic Pi and Ca2+ and (2) partially inhibited by PhPA. This Pi transporter represents a link between changes in myoplasmic [Pi] and subsequent changes in sarcoplasmic reticulum luminal [Pi]. It might therefore play a role in the delayed metabolic impairment of sarcoplasmic reticulum Ca2+ release seen during muscle fatigue, which should occur abruptly once the Ca-Pi solubility product is exceeded in the sarcoplasmic reticulum lumen.
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Affiliation(s)
- M W Fryer
- School of Physiology and Pharmacology, University of New South Wales, Sydney, Australia
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Mintz E, Guillain F. Ca2+ transport by the sarcoplasmic reticulum ATPase. BIOCHIMICA ET BIOPHYSICA ACTA 1997; 1318:52-70. [PMID: 9030255 DOI: 10.1016/s0005-2728(96)00132-6] [Citation(s) in RCA: 79] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- E Mintz
- Centre National de la Recherche Scientifique, Département de Biologie Cellulaire et Moléculaire, Centre d'Etudes de Saclay, Gif-sur-Yvette, France
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Stefanova HI, East JM, Lee AG. Covalent and non-covalent inhibitors of the phosphate transporter of sarcoplasmic reticulum. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1064:321-8. [PMID: 1827996 DOI: 10.1016/0005-2736(91)90318-3] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The sarcoplasmic reticulum (SR) of skeletal muscle contains a Pi transporter which transports Pi into the lumen of the SR, increasing the level of accumulation of Ca2+ by SR by forming insoluble salts with Ca2+. Phosphonocarboxylic acids inhibit the transport of Pi by the transporter, phosphonoformic acid itself being transported into the SR increasing the level of accumulation of Ca2+. Phenylphosphonic acid also inhibits Pi transport, distinguishing the Pi transporter of SR from the Na+/Pi transporter of brush-border membranes. Oxalate transport is also inhibited by the phosphono-carboxylic acids, consistent with the suggestion that oxalate and phosphate are carried on the same transporter. The effects of maleate are, however, not inhibited, suggesting a separate carrier for the dicarboxylic acids. Acetic anhydride and phenylglyoxal inhibit the transporter, Pi providing protection against the effects of acetic anhydride, suggesting the presence of a lysine residue at the Pi binding site. ATP provides protection against the effects of acetic anhydride and phenylglyoxal, suggesting the presence of an ATP binding site on the transporter.
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Affiliation(s)
- H I Stefanova
- Department of Biochemistry, University of Southampton, U.K
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