1999 Volume 126 Issue 2 Pages 266-270
In vivo reversible phosphorylation of Tyr-7 and Tyr-10 of the pig stomach H/K-ATPase α-chain was initially demonstrated in mammals, rat, rabbit, and pig, in the presence of vanadate+H2O2. In vitro phosphorylation has also been unequivocally demonstrated via the use of protease inhibitors during membrane H/K-ATPase preparation. An amphoretic detergent permitted each intrinsic kinase to phosphorylate each fusion protein containing the requisite Tyr residues, along with a reduction in α-chain phosphorylation. These and other data suggest that some important enzyme systems are present in the apical membrane and that they are in sufficient proximity to participate in the reversible phosphorylation of the amino terminal soluble domain of the α-chain with an unknown physiological function in the membrane embedded H/K-ATPase.
