Effect of denervation on the endogenous phosphorylating activity in the cytosol of rat skeletal muscle.

An endogenous phosphorylating activity is demonstrated in the cytosol from soleus muscle of the rat which is markedly stimulated after severing the motor nerve fibers to this muscle. The [gamma-32P]AT[ phosphotransferase reaction is heat-labile, dependent upon Mg2+ but not Ca2+ or cyclic GMP, inhibited by a cyclic AMP dependent protein kinase inhibitor, and directly related to the amount of cytosolic protein which provides the endogenous source of both the protein kinase enzyme, ATP, cyclic AMP and phosphorylatable protein substrate. The time-course of the delayed transitory stimulation of the cytosolic phosphorylating activity of the denervated soleus may involve neurotropic factors.