VANADATE INHIBITION OF SARCOPLASMIC-RETICULUM CA2+-ATPASE AND OTHER ATPASES

Vanadate is a potent inhibitor of the Ca2+-ATPase activity of sarcoplasmic reticulum in the presence of A-23187. The purified enzyme is sensitive to vanadate even in the absence of the ionophore. Ca2+ and norepinephrine protect the enzyme against inhibition of vanadate. The nonspecificity of vanadate is emphasized by the finding of inhibition of several other ATPases including the Ca2+Mg2+-ATPases of the ascites and human red cell plasma membranes, Mg2+-ATPase of the ascites plasma membrane, and the K+-ATPases of E. coli and hog gastric mucosal cell membranes. The ascites plasma membrane Ca2+-ATPase (an ecto ATPase) and mitochondrial ATPase are not inhibited by vanadate. © 1979.