Effect of hypokalemia on the abundance of HK alpha 1 and HK alpha 2 protein in the rat kidney.
An H(+)-K(+)-adenosinetriphosphatase (H(+)-K(+)-ATPase) contributes to potassium reabsorption by the collecting ducts of the rat kidney. mRNAs for two isoforms of the H(+)-K(+)-ATPase, HK alpha 1 and HK alpha 2, have been found in the rat kidney. To evaluate whether the HK alpha 1 and HK alpha 2 proteins are present in the rat kidney, microsomes enriched in HK alpha 1 or HK alpha 2 were isolated using the MiniMac magnetic separation system with antibodies directed against either HK alpha 1 (HK 12.18) or HK alpha 2 (AS 31.7). Immunoblots of rat kidney microsomal protein isolated with HK 12.18 revealed a band approximately 94 kDa in size that comigrated with the G1 fraction of the stomach. Immunoblots of rat kidney microsomal protein isolated with AS 31.7 revealed a band slightly greater than 94 kDa that comigrated with a band obtained from rat colonic microsomal protein. To examine the effect of perturbations in potassium metabolism, the abundance of the HK alpha 1 and HK alpha 2 isoforms was compared in rats fed a normal or potassium-deficient diet. A low-potassium diet increased the abundance of HK alpha 2, whereas that of HK alpha 1 was not altered. These data suggest that HK alpha 2 might be the isoform responsible for potassium conservation by the kidney.
Kraut
J A
JA
Division of Nephrology, West Los Angeles Veterans Affairs Medical Center, California, USA.
Hiura
J
J
Besancon
M
M
Smolka
A
A
Sachs
G
G
Scott
D
D
D000818:Animals; D015153:Blotting, Western; D017506:H(+)-K(+)-Exchanging ATPase / Q000378:metabolism*; D007008:Hypokalemia / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology*; D011233:Precipitin Tests; D051381:Rats; D017207:Rats, Sprague-Dawley
D007527:Isoenzymes; D017506:H(+)-K(+)-Exchanging ATPase