Effect of colchicine on sensitivity of duck salt gland Na,K-ATPase to Na+.
Low molecular mass proteins of the FXYD family that affect the sensitivity of Na,K-ATPase to Na+ and K+ are known to be present in Na,K-ATPases in various tissues. In particular, in Na,K-ATPase from kidney a gamma-subunit (with electrophoretic mobility corresponding to molecular mass of about 10 kD) is present, and Na,K-ATPase preparations from heart contain phospholemman (electrophoretic mobility of this protein corresponds to molecular mass of 13-14 kD), which provides for the interaction of heart Na,K-ATPase with cytoskeletal microtubules. Disruption of microtubules by colchicine removes phospholemman from heart Na,K-ATPase preparations. The goal of the present study was to reveal a low molecular mass protein (probably a member of FXYD family) in preparation of Na,K-ATPase from duck salt glands. Immunoprecipitation of solubilized duck salt gland Na,K-ATPase using antibodies against alpha1-subunit results in the coprecipitation of a 13 kD protein with the Na,K-ATPase complex. Treatment of homogenate from duck salt glands with colchicine removes this protein from the purified preparation of Na,K-ATPase. Simultaneously, we observed a decrease in the sensitivity of Na,K-ATPase to Na+ at pH 6.5. However, colchicine treatment of homogenate from rabbit kidney does not affect either the sensitivity of Na,K-ATPase obtained from this homogenate to Na+ or the content of 10 kD protein (presumably gamma-subunit). The data suggest that phospholemman (or a similar member of the FXYD family) tightly interacts with Na,K-ATPase from duck salt glands and binds it to microtubules, simultaneously participating in the regulation of the sensitivity of Na,K-ATPase to Na+.
Yakushev
S S
SS
Department of Biochemistry, Faculty of Biology, Lomonosov Moscow State University, Moscow, 119991, Russia.
Kumskova
E M
EM
Rubtsov
A M
AM
Lopina
O D
OD
D000818:Animals; D003078:Colchicine / Q000378:metabolism / Q000494:pharmacology*; D004372:Ducks / Q000378:metabolism*; D047468:Immunoprecipitation; D011188:Potassium / Q000378:metabolism; D021122:Protein Subunits / Q000378:metabolism; D011817:Rabbits; D012491:Salt Gland / Q000187:drug effects* / Q000378:metabolism; D012964:Sodium / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000737:chemistry / Q000378:metabolism*; D050257:Tubulin Modulators / Q000378:metabolism* / Q000494:pharmacology*
D021122:Protein Subunits; D050257:Tubulin Modulators; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium; D003078:Colchicine