Isolated bovine myocardial sarcolemma and sarcoplasmic reticulum vesicles contain tightly bound calcium-dependent protease inhibitor.
Bovine myocardial sarcolemma and sarcoplasmic reticulum vesicle preparations contained calcium-dependent protease inhibitor protein. No inhibitor was detected in mitochondrial membranes. The membrane-bound inhibitor co-purified with the marker enzymes for sarcolemma and sarcoplasmic reticulum, Na+,K+-ATPase and Ca2+,K+-ATPase respectively, on isopycnic ultracentrifugation through linear sucrose density gradients. Sarcolemma and sarcoplasmic reticulum vesicles contained about 1 mg of inhibitor per g of membrane protein. However, about one-half of the inhibitor in sarcoplasmic reticulum vesicles was not tightly associated with the membrane. The membrane-bound inhibitor may function to modulate calcium-dependent proteolytic cleavage of sarcolemmal or sarcoplasmic reticulum-associated proteins.
D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002417:Cattle; D002462:Cell Membrane / Q000032:analysis; D002499:Centrifugation, Density Gradient; D005615:Freezing; D007159:Immunologic Tests; D009206:Myocardium / Q000032:analysis*; D011480:Protease Inhibitors / Q000032:analysis*; D012508:Sarcolemma / Q000032:analysis*; D012519:Sarcoplasmic Reticulum / Q000032:analysis*
D011480:Protease Inhibitors; D002118:Calcium