Click here to close
Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly.
We suggest using a current version of Chrome,
FireFox, or Safari.
Heterologous expression of the Na(+),K(+)-ATPase gamma subunit in Xenopus oocytes induces an endogenous, voltage-gated large diameter pore.
Sha Q, Lansbery KL, Distefano D, Mercer RW, Nichols CG.
???displayArticle.abstract???
1. The gamma subunit is a specific component of the plasmalemmal Na(+),K(+)-ATPase. Like structurally related single-spanning membrane proteins such as cardiac phospholemman, Mat-8 and renal CHIF, large ion conductances are activated when gamma subunits are expressed in Xenopus oocytes. 2. Here we report critical properties of the gamma-activated conductance. The gamma-activated conductance showed non-selective cationic and anionic permeation, and extremely slow kinetics, with an activation time constant > 1 s following steps to -100 mV. 3. The gamma-activated conductance was inhibited by extracellular divalent ions including Ba(2+) (K(i) = 0.7 mM) and Ca(2+) (K(i) = 0.4 mM). 4. 2-Deoxyglucose (MW approximately 180), inulin (MW approximately 5000) and spermidine (MW approximately 148) efflux could occur through the gamma-activated conductance pathway, indicating a large pore diameter. In contrast, dextran-70 (MW approximately 70 000) did not pass through the gamma-activated channel, indicating an upper limit to the pore size of approximately 50 A (5 nm). 5. Similar conductances that are permeable to large molecules were activated by extreme hyperpolarization (> -150 mV) of uninjected oocytes. 6. We conclude that the Na(+),K(+)-ATPase gamma subunits activate Ca(2+)- and voltage-gated, non-selective, large diameter pores that are intrinsically present within the oocyte membrane.
Ackerman,
Hypotonicity activates a native chloride current in Xenopus oocytes.
1994, Pubmed,
Xenbase
Ackerman,
Hypotonicity activates a native chloride current in Xenopus oocytes.
1994,
Pubmed
,
Xenbase Arystarkhova,
The gamma subunit modulates Na(+) and K(+) affinity of the renal Na,K-ATPase.
1999,
Pubmed Attali,
A corticosteroid-induced gene expressing an "IsK-like" K+ channel activity in Xenopus oocytes.
1995,
Pubmed
,
Xenbase Attali,
The protein IsK is a dual activator of K+ and Cl- channels.
1993,
Pubmed
,
Xenbase Barhanin,
K(V)LQT1 and lsK (minK) proteins associate to form the I(Ks) cardiac potassium current.
1996,
Pubmed
,
Xenbase Béguin,
The gamma subunit is a specific component of the Na,K-ATPase and modulates its transport function.
1997,
Pubmed
,
Xenbase Ben-Efraim,
Cytoplasmic and extracellular IsK peptides activate endogenous K+ and Cl- channels in Xenopus oocytes. Evidence for regulatory function.
1996,
Pubmed
,
Xenbase Blanco,
Isozymes of the Na-K-ATPase: heterogeneity in structure, diversity in function.
1998,
Pubmed Buyse,
Expression of human pICln and ClC-6 in Xenopus oocytes induces an identical endogenous chloride conductance.
1997,
Pubmed
,
Xenbase DeVries,
Hemi-gap-junction channels in solitary horizontal cells of the catfish retina.
1992,
Pubmed Ebihara,
Properties of a nonjunctional current expressed from a rat connexin46 cDNA in Xenopus oocytes.
1993,
Pubmed
,
Xenbase Fontes,
Stimulation of ouabain binding to Na,K-ATPase in 40% dimethyl sulfoxide by a factor from Na,K-ATPase preparations.
1999,
Pubmed Forbush,
Characterization of a new photoaffinity derivative of ouabain: labeling of the large polypeptide and of a proteolipid component of the Na, K-ATPase.
1978,
Pubmed Goldstein,
Site-specific mutations in a minimal voltage-dependent K+ channel alter ion selectivity and open-channel block.
1991,
Pubmed
,
Xenbase Jones,
Embryonic expression of the putative gamma subunit of the sodium pump is required for acquisition of fluid transport capacity during mouse blastocyst development.
1997,
Pubmed Kim,
Cloning and expression of human cDNA encoding Na+, K(+)-ATPase gamma-subunit.
1997,
Pubmed Kowdley,
Anion, cation, and zwitterion selectivity of phospholemman channel molecules.
1997,
Pubmed
,
Xenbase Kowdley,
Hyperpolarization-activated chloride currents in Xenopus oocytes.
1994,
Pubmed
,
Xenbase Kuruma,
A hyperpolarization- and acid-activated nonselective cation current in Xenopus oocytes.
2000,
Pubmed
,
Xenbase Mercer,
Molecular cloning and immunological characterization of the gamma polypeptide, a small protein associated with the Na,K-ATPase.
1993,
Pubmed Minor,
The gamma subunit of the Na,K-ATPase induces cation channel activity.
1998,
Pubmed
,
Xenbase Moorman,
Unitary anion currents through phospholemman channel molecules.
1995,
Pubmed
,
Xenbase Moorman,
Phospholemman expression induces a hyperpolarization-activated chloride current in Xenopus oocytes.
1992,
Pubmed
,
Xenbase Morrison,
Mat-8, a novel phospholemman-like protein expressed in human breast tumors, induces a chloride conductance in Xenopus oocytes.
1995,
Pubmed
,
Xenbase Parker,
A calcium-independent chloride current activated by hyperpolarization in Xenopus oocytes.
1988,
Pubmed
,
Xenbase Paul,
Connexin46, a novel lens gap junction protein, induces voltage-gated currents in nonjunctional plasma membrane of Xenopus oocytes.
1991,
Pubmed
,
Xenbase Peres,
A hyperpolarization-activated chloride current in Xenopus laevis oocytes under voltage-clamp.
1983,
Pubmed
,
Xenbase Reeves,
Isolation and characterization of (Na,K)-ATPase proteolipid.
1980,
Pubmed Saito,
BAX-dependent transport of cytochrome c reconstituted in pure liposomes.
2000,
Pubmed Sanguinetti,
Coassembly of K(V)LQT1 and minK (IsK) proteins to form cardiac I(Ks) potassium channel.
1996,
Pubmed
,
Xenbase Sha,
Spermidine release from xenopus oocytes. Electrodiffusion through a membrane channel.
1996,
Pubmed
,
Xenbase Shimbo,
Viral and cellular small integral membrane proteins can modify ion channels endogenous to Xenopus oocytes.
1995,
Pubmed
,
Xenbase Sweadner,
The FXYD gene family of small ion transport regulators or channels: cDNA sequence, protein signature sequence, and expression.
2000,
Pubmed Takumi,
Cloning of a membrane protein that induces a slow voltage-gated potassium current.
1988,
Pubmed
,
Xenbase Therien,
Tissue-specific distribution and modulatory role of the gamma subunit of the Na,K-ATPase.
1997,
Pubmed Therien,
Expression and functional role of the gamma subunit of the Na, K-ATPase in mammalian cells.
1999,
Pubmed Trexler,
Voltage gating and permeation in a gap junction hemichannel.
1996,
Pubmed
,
Xenbase Tzounopoulos,
Induction of endogenous channels by high levels of heterologous membrane proteins in Xenopus oocytes.
1995,
Pubmed
,
Xenbase Wang,
MinK residues line a potassium channel pore.
1996,
Pubmed Yang,
Characterization of stretch-activated ion channels in Xenopus oocytes.
1990,
Pubmed
,
Xenbase Zampighi,
Functional and morphological correlates of connexin50 expressed in Xenopus laevis oocytes.
1999,
Pubmed
,
Xenbase Zhang,
The ion selectivity of a membrane conductance inactivated by extracellular calcium in Xenopus oocytes.
1998,
Pubmed
,
Xenbase
