Immunocytochemical localization of Na-K-ATPase α- and γ-subunits in rat kidney

Wetzel, Randall K., and Kathleen J. Sweadner. Immunocytochemical localization of Na-K-ATPase aand g-subunits in rat kidney. Am J Physiol Renal Physiol 281: F531–F545, 2001.—The g-subunit of the Na-K-ATPase is a single-span membrane protein that alters the kinetic properties of the enzyme. It is expressed in the kidney, but our initial observations indicated that it is not present in all nephron segments (Arystarkhova E, Wetzel RK, Asinovski NK, and Sweadner KJ. J Biol Chem 274: 33183–33185, 1999). Here we used triple-label confocal immunofluorescence microscopy in rat kidney with antibodies to Na-KATPase a1and g-subunits and nephron segment-specific markers. Na-K-ATPase a1-subunit stain was low but unambiguous in proximal segments, moderate in macula densa, connecting tubules, and cortical collecting ducts, high in thick ascending limb and distal convoluted tubules, and nearly undetectable in glomeruli, descending and ascending thin limb, and medullary collecting ducts. The g-subunit colocalized at staining levels similar to a1-subunit in basolateral membranes in all segments except cortical thick ascending limb and cortical collecting ducts, which had a1subunit but no detectable g-subunit stain. Selective g-subunit expression may contribute to the variations in Na-K-ATPase properties in different renal segments.