Distribution and oligomeric association of splice forms of Na(+)-K(+)-ATPase regulatory gamma-subunit in rat kidney.
Renal Na(+)-K(+)-ATPase is associated with the gamma-subunit (FXYD2), a single-span membrane protein that modifies ATPase properties. There are two splice variants with different amino termini, gamma(a) and gamma(b). Both were found in the inner stripe of the outer medulla in the thick ascending limb. Coimmunoprecipitation with each other and the alpha-subunit indicated that they were associated in macromolecular complexes. Association was controlled by ligands that affect Na(+)-K(+)-ATPase conformation. In the cortex, the proportion of the gamma(b)-subunit was markedly lower, and the gamma(a)-subunit predominated in isolated proximal tubule cells. By immunofluorescence, the gamma(b)-subunit was detected in the superficial cortex only in the distal convoluted tubule and connecting tubule, which are rich in Na(+)-K(+)-ATPase but comprise a minor fraction of cortex mass. In the outer stripe of the outer medulla and for a short distance in the deep cortex, the thick ascending limb predominantly expressed the gamma(b)-subunit. Because different mechanisms maintain and regulate Na(+) homeostasis in different nephron segments, the splice forms of the gamma-subunit may have evolved to control the renal Na(+) pump through pump properties, gene expression, or both.
Arystarkhova
Elena
E
Laboratory of Membrane Biology, Neuroscience Center, Massachusetts General Hospital, Charlestown, Massachusetts 02129, USA.
Wetzel
Randall K
RK
Sweadner
Kathleen J
KJ
D017398:Alternative Splicing / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D004591:Electrophoresis, Polyacrylamide Gel; D005455:Fluorescent Antibody Technique; D015971:Gene Expression Regulation, Enzymologic; D007679:Kidney Medulla / Q000737:chemistry* / Q000502:physiology*; D007687:Kidney Tubules, Proximal / Q000737:chemistry / Q000502:physiology; D008138:Loop of Henle / Q000737:chemistry / Q000502:physiology; D018613:Microscopy, Confocal; D009399:Nephrons / Q000737:chemistry / Q000502:physiology; D009928:Organ Specificity; D010446:Peptide Fragments / Q000276:immunology; D011233:Precipitin Tests; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000032:analysis* / Q000235:genetics* / Q000276:immunology
D010446:Peptide Fragments; D000254:Sodium-Potassium-Exchanging ATPase