Abstract
Incubation of cardiac sarcoplasmic reticulum (SR) in the presence of S-adenosyl-L-methionine, a methyl donor for the enzymatic N-methylation of phosphatidylethanolamine, increased Ca
2+-stimulated ATPase activity. The increase in Ca
2+-ATPase activity was not due to changes in the affinity for Ca
2+ and was prevented by methyl acetimidate, an inhibitor of phospholipid N-methylation. The results suggest a possible regulatory role of phospholipid N-methylation in SR Ca
2+-pump mechanism.