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Lee YHG, Cerf NT, Shalaby N, Montes MR, Clarke RJ. Bioinformatic Study of Possible Acute Regulation of Acid Secretion in the Stomach. J Membr Biol 2024; 257:79-89. [PMID: 38436710 PMCID: PMC11006737 DOI: 10.1007/s00232-024-00310-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2023] [Accepted: 02/21/2024] [Indexed: 03/05/2024]
Abstract
The gastric H+,K+-ATPase is an integral membrane protein which derives energy from the hydrolysis of ATP to transport H+ ions from the parietal cells of the gastric mucosa into the stomach in exchange for K+ ions. It is responsible for the acidic environment of the stomach, which is essential for digestion. Acid secretion is regulated by the recruitment of the H+,K+-ATPase from intracellular stores into the plasma membrane on the ingestion of food. The similar amino acid sequences of the lysine-rich N-termini α-subunits of the H+,K+- and Na+,K+-ATPases, suggests similar acute regulation mechanisms, specifically, an electrostatic switch mechanism involving an interaction of the N-terminal tail with the surface of the surrounding membrane and a modulation of the interaction via regulatory phosphorylation by protein kinases. From a consideration of sequence alignment of the H+,K+-ATPase and an analysis of its coevolution with protein kinase C and kinases of the Src family, the evidence points towards a phosphorylation of tyrosine-7 of the N-terminus by either Lck or Yes in all vertebrates except cartilaginous fish. The results obtained will guide and focus future experimental research.
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Affiliation(s)
- Yan Hay Grace Lee
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia
| | - Nicole T Cerf
- Instituto de Química y Fisicoquímica Biológica (IQUIFIB), CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Nicholas Shalaby
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia
| | - Mónica R Montes
- Instituto de Química y Fisicoquímica Biológica (IQUIFIB), CONICET, Universidad de Buenos Aires, Buenos Aires, Argentina
| | - Ronald J Clarke
- School of Chemistry, University of Sydney, Sydney, NSW, 2006, Australia.
- The University of Sydney Nano Institute, Sydney, NSW, 2006, Australia.
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2
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Bogdanova OV, Kot LI, Lavrova KV, Bogdanov VB, Sloan EK, Beregova TV, Ostapchenko LI. Modulation of protein tyrosine phosphorylation in gastric mucosa during re-epithelization processes. World J Biol Chem 2010; 1:338-47. [PMID: 21537468 PMCID: PMC3083939 DOI: 10.4331/wjbc.v1.i11.338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2010] [Revised: 09/13/2010] [Accepted: 09/20/2010] [Indexed: 02/05/2023] Open
Abstract
AIM: To investigate the role of protein tyrosine phosphorylation in gastric wound formation and repair following ulceration.
METHODS: Gastric lesions were induced in rats using restraint cold stress. To investigate the effect of oxidative and nitrosative cell stress on tyrosine phosphorylation during wound repair, total activity of protein tyrosine kinase (PTK), protein tyrosine phosphatase (PTP), antioxidant enzymes, nitric oxide synthase (NOS), 2’,5’-oligoadenylate synthetase, hydroxyl radical and zinc levels were assayed in parallel.
RESULTS: Ulcer provocation induced an immediate decrease in tyrosine kinase (40% in plasma membranes and 56% in cytosol, P < 0.05) and phosphatase activity (threefold in plasma membranes and 3.3-fold in cytosol), followed by 2.3-2.4-fold decrease (P < 0.05) in protein phosphotyrosine content in the gastric mucosa. Ulceration induced no immediate change in superoxide dismutase (SOD) activity, 30% increase (P < 0.05) in catalase activity, 2.3-fold inhibition (P < 0.05) of glutathione peroxidase, 3.3-fold increase (P < 0.05) in hydroxyl radical content, and 2.3-fold decrease (P < 0.05) in zinc level in gastric mucosa. NOS activity was three times higher in gastric mucosa cells after cold stress. Following ulceration, PTK activity increased in plasma membranes and reached a maximum on day 4 after stress (twofold increase, P < 0.05), but remained inhibited (1.6-3-fold decrease on days 3, 4 and 5, P < 0.05) in the cytosol. Tyrosine phosphatases remained inhibited both in membranes and cytosol (1.5-2.4-fold, P < 0.05). NOS activity remained increased on days 1, 2 and 3 (3.8-, 2.6-, 2.2-fold, respectively, P < 0.05). Activity of SOD increased 1.6 times (P < 0.05) days 4 and 5 after stress. Catalase activity normalized after day 2. Glutathione peroxidase activity and zinc level decreased (3.3- and 2-fold, respectively, P < 0.05) on the last day. Activity of 2’,5’-oligoadenylate synthethase increased 2.8-fold (P < 0.05) at the beginning, and 1.6-2.3-fold (P < 0.05) during ulcer recuperation, and normalized on day 5, consistent with slowing of inflammation processes.
CONCLUSION: These studies show diverse changes in total tyrosine kinase activity in gastric mucosa during the recovery process. Oxidative and nitrosative stress during lesion formation might lead to the observed reduction in tyrosine phosphorylation during ulceration.
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Affiliation(s)
- Olena V Bogdanova
- Olena V Bogdanova, Larysa I Kot, Kateryna V Lavrova, Ludmyla I Ostapchenko, Department of Biochemistry, Taras Shevchenko National University of Kyiv, Kyiv, 01033, Ukraine
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3
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Abe K, Tani K, Nishizawa T, Fujiyoshi Y. Inter-subunit interaction of gastric H+,K+-ATPase prevents reverse reaction of the transport cycle. EMBO J 2009; 28:1637-43. [PMID: 19387495 DOI: 10.1038/emboj.2009.102] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2009] [Accepted: 03/10/2009] [Indexed: 11/09/2022] Open
Abstract
The gastric H(+),K(+)-ATPase is an ATP-driven proton pump responsible for generating a million-fold proton gradient across the gastric membrane. We present the structure of gastric H(+),K(+)-ATPase at 6.5 A resolution as determined by electron crystallography of two-dimensional crystals. The structure shows the catalytic alpha-subunit and the non-catalytic beta-subunit in a pseudo-E(2)P conformation. Different from Na(+),K(+)-ATPase, the N-terminal tail of the beta-subunit is in direct contact with the phosphorylation domain of the alpha-subunit. This interaction may hold the phosphorylation domain in place, thus stabilizing the enzyme conformation and preventing the reverse reaction of the transport cycle. Indeed, truncation of the beta-subunit N-terminus allowed the reverse reaction to occur. These results suggest that the beta-subunit N-terminus prevents the reverse reaction from E(2)P to E(1)P, which is likely to be relevant for the generation of a large H(+) gradient in vivo situation.
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Affiliation(s)
- Kazuhiro Abe
- Department of Biophysics, Faculty of Science, Kyoto University, Kyoto, Japan
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4
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Abstract
Na,K-ATPase is responsible for maintaining the correct concentrations of sodium and potassium in lens cells. Na,K-ATPase activity is different in the two cell types that make up the lens, epithelial cells and fibers; specific activity in the epithelium is higher than in fibers. In some parts of the fiber mass Na,K-ATPase activity is barely detectable. There is a large body of evidence that suggests Na,K-ATPase-mediated ion transport by the epithelium contributes significantly to the regulation of ionic composition in the entire lens. In some species different Na,K-ATPase isoforms are present in epithelium and fibers but in general, fibers and epithelium express a similar amount of Na,K-ATPase protein. Turnover of Na,K-ATPase by protein synthesis may contribute to preservation of high Na,K-ATPase activity in the epithelium. In ageing lens fibers, oxidation, and glycation may decrease Na,K-ATPase activity. Na,K-ATPase activity in lens fibers and epithelium also may be subject to regulation as the result of protein tyrosine phosphorylation. Moreover, activation of G protein-coupled receptors by agonists such as endothelin-1 elicits changes of Na,K-ATPase activity. The asymmetrical distribution of Na,K-ATPase activity in the epithelium and fibers may contribute to ionic currents that flow in and around the lens. Studies on human cataract and experimental cataract in animals reveal changes of Na,K-ATPase activity but no clear pattern is evident. However, there is a convincing link between abnormal elevation of lens sodium and the opacification of the lens cortex that occurs in age-related human cataract.
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Affiliation(s)
- Nicholas A Delamere
- Department of Ophthalmology and Visual Sciences, School of Medicine, Louisville, Kentucky, USA.
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5
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Bozulic LD, Dean WL, Delamere NA. The influence of protein tyrosine phosphatase-1B on Na,K-ATPase activity in lens. J Cell Physiol 2004; 200:370-6. [PMID: 15254964 DOI: 10.1002/jcp.20029] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The abnormal sodium content of many cataracts suggests Na,K-ATPase is vital for maintenance of eye lens transparency. Since tyrosine phosphorylation is considered a possible regulatory mechanism for Na,K-ATPase, experiments were conducted to test the influence of protein tyrosine phosphatase-1B (PTP-1B) on Na,K-ATPase activity. Membrane material was isolated separately from porcine lens epithelium and fiber cells. Tyrosine phosphoproteins, Na,K-ATPase alpha1 polypeptide and PTP-1B were examined by Western blot. Na,K-ATPase activity was determined by measuring ATP hydrolysis in the presence or absence of ouabain. Western blot analysis revealed tyrosine phosphorylation of multiple membrane proteins in both lens cell types, the differentiated fiber cells and non-differentiated epithelium. When membrane material was subjected to immunoprecipitation using an antibody directed against Na,K-ATPase alpha1, a colocalized phosphotyrosine band was detected in lens fibers but not epithelium. Incubation with PTP-1B caused a approximately 50% increase of Na,K-ATPase activity in fiber membrane material. Na,K-ATPase activity in lens epithelium membrane material was not significantly altered by PTP-1B treatment even though PTP-1B was demonstrated to cause dephosphorylation of multiple membrane proteins in the epithelium as well as fibers. While endogenous PTP-1B was detected in both cell types, endogenous tyrosine phosphatase activity was low in both epithelium and fiber membrane material. The results illustrate endogenous tyrosine phosphorylation of Na,K-ATPase alpha1 polypeptide in fibers. Na,K-ATPase alpha1 in lens fibers may be a potential target for PTP-1B.
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Affiliation(s)
- Larry D Bozulic
- Department of Biochemistry and Molecular Biology, University of Louisville, School of Medicine, Louisville, Kentucky 40292, USA
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6
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Bozulic LD, Dean WL, Delamere NA. The influence of Lyn kinase on Na,K-ATPase in porcine lens epithelium. Am J Physiol Cell Physiol 2004; 286:C90-6. [PMID: 12967913 DOI: 10.1152/ajpcell.00174.2003] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
Na,K-ATPase is essential for the regulation of cytoplasmic Na+ and K+ levels in lens cells. Studies on the intact lens suggest activation of tyrosine kinases may inhibit Na,K-ATPase function. Here, we tested the influence of Lyn kinase, a Src-family member, on tyrosine phosphorylation and Na,K-ATPase activity in membrane material isolated from porcine lens epithelium. Western blot studies indicated the expression of Lyn in lens cells. When membrane material was incubated in ATP-containing solution containing partially purified Lyn kinase, Na,K-ATPase activity was reduced by approximately 38%. Lyn caused tyrosine phosphorylation of multiple protein bands. Immunoprecipitation and Western blot analysis showed Lyn treatment causes an increase in density of a 100-kDa phosphotyrosine band immunopositive for Na,K-ATPase alpha1 polypeptide. Incubation with protein tyrosine phosphatase 1B (PTP-1B) reversed the Lyn-dependent tyrosine phosphorylation increase and the change of Na,K-ATPase activity. The results suggest that Lyn kinase treatment of a lens epithelium membrane preparation is able to bring about partial inhibition of Na,K-ATPase activity associated with tyrosine phosphorylation of multiple membrane proteins, including the Na,K-ATPase alpha1 catalytic subunit.
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Affiliation(s)
- Larry D Bozulic
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Louisville, Louisville, KY 40202, USA
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7
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Asano S, Morii M, Takeguchi N. Molecular and Cellular Regulation of the Gastric Proton Pump. Biol Pharm Bull 2004; 27:1-12. [PMID: 14743830 DOI: 10.1248/bpb.27.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The gastric H+, K+-ATPase is a proton pump that is responsible for gastric acid secretion and that actively transports protons and K+ ions in opposite directions to generate in excess of a million-fold gradient across the membrane under physiological conditions. This pump is also a target molecule of proton pump inhibitors which are used for the clinical treatment of hyperacidity. In this review, we wish to summarize the molecular regulation of this pump based on mutational studies, particularly those used for the identification of binding sites for cations and specific inhibitors. Recent reports by Toyoshima et al (2000, 2002) presented precise three-dimensional (3-D) structures of the sarcoplasmic reticulum (SR) Ca2+-ATPase, which belongs to the same family as the gastric H+, K+-ATPase. We have studied the structure-function relationships for the gastric H+, K+-ATPase using 3-D structures constructed by homology modeling of the related SR Ca2+-ATPase, which was used as a template molecule. We also discuss in this review, the regulation of cell surface expression and synthesis control of the gastric proton pump.
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Affiliation(s)
- Shinji Asano
- Life Scientific Research Center, Toyama Medican and Pharmaceutical University, 2630 Sugitani, Toyama 930-0194, Japan.
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8
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Cornelius F, Mahmmoud YA. Direct activation of gastric H,K-ATPase by N-terminal protein kinase C phosphorylation. Comparison of the acute regulation mechanisms of H,K-ATPase and Na,K-ATPase. Biophys J 2003; 84:1690-700. [PMID: 12609871 PMCID: PMC1302738 DOI: 10.1016/s0006-3495(03)74977-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
In this study we compared the protein kinase dependent regulation of gastric H,K-ATPase and Na,K-ATPase. The protein kinase A/protein kinase C (PKA/PKC) phosphorylation profile of H,K-ATPase was very similar to the one found in the Na,K-ATPase. PKC phosphorylation was taking place in the N-terminal part of the alpha-subunit with a stoichiometry of approximately 0.6 mol Pi/mole alpha-subunit. PKA phosphorylation was in the C-terminal part and required detergent, as is also found for the Na,K-ATPase. The stoichiometry of PKA-induced phosphorylation was approximately 0.7 mol Pi/mole alpha-subunit. Controlled proteolysis of the N-terminus abolished PKC phosphorylation of native H,K-ATPase. However, after detergent treatment additional C-terminal PKC sites became exposed located at the beginning of the M5M6 hairpin and at the cytoplasmic L89 loop close to the inner face of the plasma membrane. N-terminal PKC phosphorylation of native H,K-ATPase alpha-subunit was found to stimulate the maximal enzyme activity by 40-80% at saturating ATP, depending on pH. Thus, a direct modulation of enzyme activity by PKC phosphorylation could be demonstrated that may be additional to the well-known regulation of acid secretion by recruitment of H,K-ATPase to the apical membranes of the parietal cells. Moreover, a distinct difference in the regulation of H,K-ATPase and Na,K-ATPase is the apparent absence of any small regulatory proteins associated with the H,K-ATPase.
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9
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Fujitani N, Kanagawa M, Aizawa T, Ohkubo T, Kaya S, Demura M, Kawano K, Nishimura SI, Taniguchi K, Nitta K. Structure determination and conformational change induced by tyrosine phosphorylation of the N-terminal domain of the alpha-chain of pig gastric H+/K+-ATPase. Biochem Biophys Res Commun 2003; 300:223-9. [PMID: 12480547 DOI: 10.1016/s0006-291x(02)02794-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
It has been well established that phosphorylation is an important reaction for the regulation of protein functions. In the N-terminal domain of the alpha-chain of pig gastric H(+)/K(+)-ATPase, reversible sequential phosphorylation occurs at Tyr 10 and Tyr 7. In this study, we determined the structure of the peptide involving the residues from Gly 2 to Gly 34 of pig gastric H(+)/K(+)-ATPase and investigated the tyrosine phosphorylation-induced conformational change using CD and NMR experiments. The solution structure showed that the N-terminal fragment has a helical conformation, and the peptide adopted two alpha-helices in 50% trifluoroethanol (TFE) solvent, suggesting that the peptide has a high helical propensity under hydrophobic conditions. Furthermore, the CD and NMR data suggested that the structure of the N-terminal fragment becomes more disordered as a result of phosphorylation of Tyr 10. This conformational change induced by the phosphorylation of Tyr 10 might be an advantageous reaction for sequential phosphorylation and may be important for regulating the function of H(+)/K(+)-ATPase.
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Affiliation(s)
- Naoki Fujitani
- Division of Biological Sciences, Graduate School of Science, Hokkaido University, Sapporo 060-0810, Japan
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10
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Féraille E, Doucet A. Sodium-potassium-adenosinetriphosphatase-dependent sodium transport in the kidney: hormonal control. Physiol Rev 2001; 81:345-418. [PMID: 11152761 DOI: 10.1152/physrev.2001.81.1.345] [Citation(s) in RCA: 340] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Tubular reabsorption of filtered sodium is quantitatively the main contribution of kidneys to salt and water homeostasis. The transcellular reabsorption of sodium proceeds by a two-step mechanism: Na(+)-K(+)-ATPase-energized basolateral active extrusion of sodium permits passive apical entry through various sodium transport systems. In the past 15 years, most of the renal sodium transport systems (Na(+)-K(+)-ATPase, channels, cotransporters, and exchangers) have been characterized at a molecular level. Coupled to the methods developed during the 1965-1985 decades to circumvent kidney heterogeneity and analyze sodium transport at the level of single nephron segments, cloning of the transporters allowed us to move our understanding of hormone regulation of sodium transport from a cellular to a molecular level. The main purpose of this review is to analyze how molecular events at the transporter level account for the physiological changes in tubular handling of sodium promoted by hormones. In recent years, it also became obvious that intracellular signaling pathways interacted with each other, leading to synergisms or antagonisms. A second aim of this review is therefore to analyze the integrated network of signaling pathways underlying hormone action. Given the central role of Na(+)-K(+)-ATPase in sodium reabsorption, the first part of this review focuses on its structural and functional properties, with a special mention of the specificity of Na(+)-K(+)-ATPase expressed in renal tubule. In a second part, the general mechanisms of hormone signaling are briefly introduced before a more detailed discussion of the nephron segment-specific expression of hormone receptors and signaling pathways. The three following parts integrate the molecular and physiological aspects of the hormonal regulation of sodium transport processes in three nephron segments: the proximal tubule, the thick ascending limb of Henle's loop, and the collecting duct.
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Affiliation(s)
- E Féraille
- Division of Nephrology, Geneva University Hospital, Geneva, Switzerland.
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11
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Asano S, Miwa K, Yashiro H, Tabuchi Y, Takeguchi N. Significance of lysine/glycine cluster structure in gastric H+,K+-ATPase. THE JAPANESE JOURNAL OF PHYSIOLOGY 2000; 50:419-28. [PMID: 11082540 DOI: 10.2170/jjphysiol.50.419] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Gastric H+,K+-ATPase consists of alpha- and beta-subunits. The catalytic alpha-subunit contains a very unique structure consisting of lysine and glycine clusters, KKK(or KKKK)AG(G/R)GGGK-(K/R)K, in the amino-terminal cytoplasmic region. This structure is well conserved in all gastric H+,K+-ATPases from different animal species, and was postulated to be the site controlling the access of cations (or proton) to its binding site. In this report, we studied the role of this unique structure by expressing several H+,K+-ATPase mutants of the alpha-subunit together with the wild-type beta-subunit in HEK-293 cells. Even after replacing all the positively-charged amino acid residues (six lysines and one arginine) in the cluster with alanine or removing all the glycine residues in the cluster, the mutants preserved the H+,K+-ATPase activity, and showed similar affinity for ATP and K+ as well as similar pH profiles as those of wild-type H+,K+-ATPase, indicating that the cluster is not indispensable for H+,K+-ATPase activity and not directly involved in determination of the affinity for cation (proton).
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Affiliation(s)
- S Asano
- Molecular Genetics Research Center, Toyama Medical and Pharmaceutical University, Toyama, 930-0194 Japan.
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12
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Abstract
The physiologic function of an ion pump is determined, in part, by its subcellular localization and by the cellular mechanisms that modulate its activity. The Na,K-ATPase and the gastric H,K-ATPase are two closely related members of the P-type family of ion transporting ATPases. Despite their homology, these pumps are sorted to different domains in polarized epithelial cells and their enzymatic activities are subject to distinct regulatory pathways. The molecular signals responsible for these properties have begun to be elucidated. It appears that a complex array of inter- and intra-molecular interactions govern these proteins' trafficking, distribution and catalytic capacity.
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Affiliation(s)
- L A Dunbar
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06525, USA
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13
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Féraille E, Carranza ML, Gonin S, Béguin P, Pedemonte C, Rousselot M, Caverzasio J, Geering K, Martin PY, Favre H. Insulin-induced stimulation of Na+,K(+)-ATPase activity in kidney proximal tubule cells depends on phosphorylation of the alpha-subunit at Tyr-10. Mol Biol Cell 1999; 10:2847-59. [PMID: 10473631 PMCID: PMC25522 DOI: 10.1091/mbc.10.9.2847] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Phosphorylation of the alpha-subunit of Na+,K(+)-ATPase plays an important role in the regulation of this pump. Recent studies suggest that insulin, known to increase solute and fluid reabsorption in mammalian proximal convoluted tubule (PCT), is stimulating Na+,K(+)-ATPase activity through the tyrosine phosphorylation process. This study was therefore undertaken to evaluate the role of tyrosine phosphorylation of the Na+,K(+)-ATPase alpha-subunit in the action of insulin. In rat PCT, insulin and orthovanadate (a tyrosine phosphatase inhibitor) increased tyrosine phosphorylation level of the alpha-subunit more than twofold. Their effects were not additive, suggesting a common mechanism of action. Insulin-induced tyrosine phosphorylation was prevented by genistein, a tyrosine kinase inhibitor. The site of tyrosine phosphorylation was identified on Tyr-10 by controlled trypsinolysis in rat PCTs and by site-directed mutagenesis in opossum kidney cells transfected with rat alpha-subunit. The functional relevance of Tyr-10 phosphorylation was assessed by 1) the abolition of insulin-induced stimulation of the ouabain-sensitive (86)Rb uptake in opossum kidney cells expressing mutant rat alpha1-subunits wherein tyrosine was replaced by alanine or glutamine; and 2) the similarity of the time course and dose dependency of the insulin-induced increase in ouabain-sensitive (86)Rb uptake and tyrosine phosphorylation. These findings indicate that phosphorylation of the Na+,K(+)-ATPase alpha-subunit at Tyr-10 likely participates in the physiological control of sodium reabsorption in PCT.
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Affiliation(s)
- E Féraille
- Division de Néphrologie, Fondation pour Recherches Médicales, 1211 Genève 4, Switzerland.
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Affiliation(s)
- M G Palmgren
- Department of Plant Biology, Royal Veterinary and Agricultural University, Copenhagen, Denmark.
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15
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Kaya S, Mårdh S. Protein kinase-dependent phosphorylation of H,K ATPase-containing membranes from rat and pig stomachs. ACTA PHYSIOLOGICA SCANDINAVICA 1998; 162:57-62. [PMID: 9492902 DOI: 10.1046/j.1365-201x.1998.0269f.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Previously H,K ATPase preparations from pig stomach were shown to contain intrinsic protein kinase activities which phosphorylated specific tyrosine and serine residues in the N-terminal of the alpha-chain of H,K ATPase (Togawa et al. 1996). In the present investigation, pig H,K ATPase-containing membrane preparations were compared with rat preparations. In contrast to results obtained with the alpha-subunit of H,K ATPase from pig, phosphorylation was not observed in the rat enzyme. Addition of rat preparations to the pig preparations resulted in decreased phosphorylation in pig preparations. To follow the phosphorylation of membrane proteins in vivo, 32P-loaded gastric cells prepared from rat were stimulated with several secretagogues. Proteins with molecular weights of about 120 and 80 kDa were markedly phosphorylated upon stimulation, but the alpha-subunit of H,K ATPase was not. These results suggest that phosphorylation of tyrosine or serine residues of H,K ATPase found in pig H,K ATPase preparations may not be involved in the acid secretion pathway.
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Affiliation(s)
- S Kaya
- Department of Cell Biology, Faculty of Health Sciences, Linköping University, Sweden
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16
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Togawa K, Kaya S, Mori M, Shimada A, Imagawa T, Taniguchi K, Mårdh S, Corbin J, Kikkawa U. Phosphorylation of Tyr7, Tyr10, and Ser27 of alpha-chain in H+,K(+)-ATPase by intrinsic and extrinsic kinases. Ann N Y Acad Sci 1997; 834:582-4. [PMID: 9405868 DOI: 10.1111/j.1749-6632.1997.tb52325.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Affiliation(s)
- K Togawa
- Graduate School of Science, Hokkaido University, Sapporo, Japan
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