K. Sweadner
Oct 10, 1977
Citations
0
Influential Citations
32
Citations
Journal
Biochemical and biophysical research communications
Abstract
Abstract Monofunctional imidoesters such as ethyl acetimidate can induce crosslinking of subunits of the (Na+ + K+) ion-stimulated ATPase. The cross-linked product is shown to be composed of equal parts of two subunits: one phosphorylated by γ-[32P]ATP, the other a glycoprotein. Because crosslinking of proteins by imidoesters normally requires reaction at both ends of a bifunctional reagent, the reaction is unexpected. A model for the reaction is proposed, in which a favorably positioned amino group on one subunit displaces the amidino group on the other, forming a covalent diamidino crosslink between the two subunits. Reaction with imidoesters also partially inhibits the Na,K-ATPase and reduces the sensitivity of the phosphorylated form of the enzyme to potassium ion. This modification resembles the effect of ouabain, a specific inhibitor of Na,K-ATPase, and is independent of crosslinking.