Proteolysis of skeletal muscle adenylate cyclase Destruction and reconstitution of flouride and guanylnucleotide sensitivity

Adenylate cyclase was measured in skeletal muscle plasma membranes incubated with subtilisin. Under specific conditions the protease preferentially inactivated flouride and guanylnucleotide sensitivity. Following protease treatment, membranes were solubilized with Lubrol 12A9 and subjected to ion-exchange chromatography. Adenylate cyclase was eluted with 200 mM NaCl; the enzyme recovered was completely unresponsive to either NaF or guanylyl imidodiphosphate. Responsiveness to the two ligands was restored by adding a heart fraction in which basal activity had been destroyed by heating at 40°C or by adding a soluble skeletal muscle fraction in which basal activity had been largely destroyed by N-ethylmaleimide. The solubilized subtilisin-treated skeletal muscle preparation may serve as a source of catalytic activity for the study and purification of regulatory factors for adenylate cyclase.