The gamma subunit of the Na,K-ATPase induces cation channel activity

Minor, Nicole T.; Sha, Qun; Nichols, Colin G.; Mercer, Robert W.

doi:10.1073/pnas.95.11.6521

Cited by 62 publications

(61 citation statements)

References 27 publications

(24 reference statements)

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“…Cloning and Sequencing-First strand cDNA synthesis was carried out in a total reaction volume of 20 l containing 5 g of total rectal gland RNA, 75 mM Tris-HCl, pH 8.3, 3 mM MgCl 2 , 10 mM DTT, 10 M oligo(dT) [12][13][14][15][16][17][18] , 1 mM each of deoxyribonucleotide triphosphates (dNTPs; dATP, dGTP, dCTP, and dTTP), and 200 units of Superscript II (Invitrogen, Paisley, UK). The reaction was incubated at 45°C for 2 h and then stored frozen at Ϫ20°C for use in PCR.…”

Section: Methodsmentioning

confidence: 99%

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Regulation of Na,K-ATPase by PLMS, the Phospholemman-like Protein from Shark

Mahmmoud

Cramb

Maunsbach

et al. 2003

Journal of Biological Chemistry

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In Na,K-ATPase membrane preparations from shark rectal glands, we have previously identified an FXYD domain-containing protein, phospholemman-like protein from shark, PLMS. This protein was shown to associate and modulate shark Na,K-ATPase activity in vitro. Here we describe the complete coding sequence, expression, and cellular localization of PLMS in the rectal gland of the shark Squalus acanthias. The mature protein contained 74 amino acids, including the N-terminal FXYD motif and a C-terminal protein kinase multisite phosphorylation motif. The sequence is preceded by a 20 amino acid candidate cleavable signal sequence. Immunogold labeling of the Na,K-ATPase ␣-subunit and PLMS showed the presence of ␣ and PLMS in the basolateral membranes of the rectal gland cells and suggested their partial colocalization. Furthermore, through controlled proteolysis, the C terminus of PLMS containing the protein kinase phosphorylation domain can be specifically cleaved. Removal of this domain resulted in stimulation of maximal Na,K-ATPase activity, as well as several partial reactions. Both the E 1 ϳP 3 E 2 -P reaction, which is partially rate-limiting in shark, and the K ؉ deocclusion reaction, E 2 (K) 3 E 1 , are accelerated. The latter may explain the finding that the apparent Na ؉ affinity was increased by the specific C-terminal PLMS truncation. Thus, these data are consistent with a model where interaction of the phosphorylation domain of PLMS with the Na,K-ATPase ␣-subunit is important for the modulation of shark Na,K-ATPase activity.

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Section: Methodsmentioning

confidence: 99%

“…This family includes phospholemman (PLM or FXYD1) (14), the ␥-subunit (FXYD2) (15), mammary tumor protein of 8-kDa molecular mass (MAT-8 or FXYD3) (16), channel-inducing factor (CHIF or FXYD4) (17), related to ion channel (RIC or FYXD5) (18), as well as FXYD6 and FXYD7.…”

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confidence: 99%

Regulation of Na,K-ATPase by PLMS, the Phospholemman-like Protein from Shark

Mahmmoud

Cramb

Maunsbach

et al. 2003

Journal of Biological Chemistry

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“…There is evidence that it raises the affinity for ATP (13) by stabilizing the E 1 conformation of the Na-K-ATPase (12,13), and also that it reduces the enzyme's affinity for Na ϩ at cytoplasmic sites (14) by increasing the affinity of cytoplasmic K ϩ as a competitor for cytoplasmic Na ϩ (15). The ␥ subunit also affects the affinity for extracellualr K ϩ ions in a voltage-sensitive fashion and can induce nonselective cation channel activity (16). The ␥ subunit may be a tissue-specific regulator, and some of the functions described above may serve cells well in their defense against a hypertonic environment.…”

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confidence: 99%

The expression of the γ subunit of Na-K-ATPase is regulated by osmolality via C-terminal Jun kinase and phosphatidylinositol 3-kinase-dependent mechanisms

Capasso

Rivard

Berl

2001

Proc. Natl. Acad. Sci. U.S.A.

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The ␣ and ␤ subunits of Na-K-ATPase are up-regulated by hypertonicity in inner-medullary collecting duct cells adapted to survive in hypertonic conditions. We examined the regulation of the ␥ subunit by hypertonicity. Although cultured inner-medullary collecting duct cells lacked the ␥ subunits, both variants ␥a and ␥b were expressed in cells adapted to 600 and 900 mosmol͞KgH2O. This expression was reversible with a half-time of 17.2 ؎ 0.5 h. The message of the ␥ subunit was absent in isotonic conditions and increased with higher tonicity in adapted cells. In acute experiments the appearance of the ␥ subunit was found to be both time-dependent (>24 h) and osmolality-dependent (>500 mosmol͞KgH2O). No induction was noted with urea and only minimal induction with mannitol. Increasing concentrations of the phosphatidylinositol 3-kinase inhibitor LY294002 resulted in a dose-dependent decrement in the expression of the ␥ subunit with total abolition at 10 M. This was associated with a decrease in cell viability as <20% survived the treatment with 10 M of LY294002. Neither inhibition of extracellular response kinase nor p38 mitogen-activated protein kinase inhibited osmotic induction of the ␥ subunit. In contrast, cells transfected with a dominant negative c-Jun N-terminal kinase 2-APF construct displayed complete inhibition of the ␥ subunit. Such cells have accelerated loss of viability in hypertonic conditions. This study describes the regulation of the ␥ subunit of Na-K-ATPase by hypertonicity. This regulation is transcriptionally regulated and involves signaling mediated by phosphatidylinositol 3-kinase and c-Jun N-terminal kinase 2 pathways.

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“…The working hypothesis is that all family members modulate the pump kinetics in vivo and function as tissue-specific modulators of the Na,KATPase (9 -11). However, other functions for FXYD proteins have also been suggested (12)(13)(14)(15)(16).…”

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confidence: 99%

Interaction with the Na,K-ATPase and Tissue Distribution of FXYD5 (Related to Ion Channel)

Lubarski

Pihakaski-Maunsbach

Karlish

et al. 2005

Journal of Biological Chemistry

132

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FXYD5 (related to ion channel, dysadherin) is a member of the FXYD family of single span type I membrane proteins. Five members of this group have been shown to interact with the Na,KATPase and to modulate its properties. However, FXYD5 is structurally different from other family members and has been suggested to play a role in regulating E-cadherin and promoting metastasis (Ino, Y., Gotoh, M., Sakamoto, M., Tsukagoshi, K., and Hirohashi, S. (2002) Proc. Natl. Acad. Sci. U. S. A. 99, 365-370). The goal of this study was to determine whether FXYD5 can modulate the Na,KATPase activity, establish its cellular and tissue distribution, and characterize its biochemical properties. Anti-FXYD5 antibodies detected a 24-kDa polypeptide that was preferentially expressed in kidney, intestine, spleen, and lung. In kidney, FXYD5 resides in the basolateral membrane of the connecting tubule, the collecting tubule, and the intercalated cells of the collecting duct. However, there is also labeling of the apical membrane in long thin limb of Henle's loop. FXYD5 was effectively immunoprecipitated by antibodies to the ␣ subunit of Na,K-ATPase and the anti-FXYD5 antibody immunoprecipitates ␣. Co-expressing FXYD5 with the ␣1 and ␤1 subunits of the Na,K-ATPase in Xenopus oocytes elicited a more than 2-fold increase in pump activity, measured either as ouabainblockable outward current or as ouabain-sensitive 86 Rb ؉ uptake.Thus, as found with other FXYD proteins, FXYD5 interacts with the Na,K-ATPase and modulates its properties.Work in several laboratories led to the identification of a family of proteins, named after the common motif FXYD (1). Five members of this group have been shown to interact with the Na,K-ATPase and elicit different effects on its kinetics. These are as follows: FXYD1 (phospholemman, PLM), 3 (2); FXYD2 (the ␥ subunit of Na,K-ATPase, ␥) (3); FXYD3 (Mat-8) (4); FXYD4 (corticosteroid hormone-induced factor, CHIF) (5); and FXYD7 (6). In addition, a PLM-like protein from shark rectal gland has been characterized (7,8). The remaining two family members FXYD5 (related to ion channel, dysadherin) and FXYD6 have not yet been analyzed for possible interactions with the Na,K-ATPase. The working hypothesis is that all family members modulate the pump kinetics in vivo and function as tissue-specific modulators of the Na,KATPase (9 -11). However, other functions for FXYD proteins have also been suggested (12-16).FXYD proteins are type I membrane proteins with an extracellular N terminus (sometimes including a signal peptide), a single transmembrane domain, and an intracellular C terminus. With the exception of FXYD5, the extracellular domain is shorter than 40 amino acids, including a cleavable signal peptide. In the case of FXYD5, the extracellular domain is long, Ͼ140 amino acids. On the other hand, FXYD5 has the shortest intracellular C-terminal segment of only 15 amino acids. FXYD5 has been cloned as a tissue-specific and developmentally regulated gene induced by the oncoprotein E2a-Pbx1 and termed "related to ion channel...

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The gamma subunit of the Na,K-ATPase induces cation channel activity

Cited by 62 publications

References 27 publications

Regulation of Na,K-ATPase by PLMS, the Phospholemman-like Protein from Shark

Regulation of Na,K-ATPase by PLMS, the Phospholemman-like Protein from Shark

The expression of the γ subunit of Na-K-ATPase is regulated by osmolality via C-terminal Jun kinase and phosphatidylinositol 3-kinase-dependent mechanisms

Interaction with the Na,K-ATPase and Tissue Distribution of FXYD5 (Related to Ion Channel)

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