Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P67775 (alpha isoform)
 797 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Estimations of concentration of the labile sodium pump inhibitor isolated from human peritoneal dialysate were made using supercritical fluid chromatography coupled to flame ionization detection to determine the quantity of this factor in half of a purified preparation of the factor compared to the bioactivity of the other half in different assays. Ouabain was used for comparison. The labile factor appeared to be 30 times more effective than ouabain against canine renal [Na,K]ATPase. Moreover, this same factor appeared to be approximately 1,000 times more potent than ouabain in causing vascular smooth muscle contraction. The differences between this labile sodium pump inhibitor and ouabain most likely reflect their respective binding affinities. The assay differences in half maximal response to the labile sodium pump inhibitor may be due to differences in sodium pump alpha isoform sensitivity.
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PMID:A labile sodium pump inhibitor from the peritoneal dialysate of hypertensive renal failure patients: estimates of potency. 968 17

The Na,K-ATPase is a major ion transport protein found in higher eukaryotic cells. The enzyme is composed of two subunits, alpha and beta, and tissue-specific isoforms exist for each of these, alpha1, alpha2 and alpha3 and beta1, beta2 and beta3. We have proposed that an additional alpha isoform, alpha4, exists based on genomic and cDNA cloning. The mRNA for this gene is expressed in rats and humans, exclusively in the testis, however the expression of a corresponding protein has not been demonstrated. In the current study, the putative alpha4 isoform has been functionally characterized as a novel isoform of the Na,K-ATPase in both rat testis and in alpha4 isoform cDNA transfected 3T3 cells. Using an alpha4 isoform-specific polyclonal antibody, the protein for this novel isoform is detected for the first time in both rat testis and in transfected cell lines. Ouabain binding competition assays reveal the presence of high affinity ouabain receptors in both rat testis and in transfected cell lines that have identical KD values. Further studies of this high affinity ouabain receptor show that it also has high affinities for both Na+ and K+. The results from these experiments definitively demonstrate the presence of a novel isoform of the Na,K-ATPase in testis.
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PMID:Characterization of the fourth alpha isoform of the Na,K-ATPase. 1022 50