STUDIES ON PHOSPHORYLASE <i>b</i> KINASE FROM NEUTRAL TISSUES¹

It is concluded that the mechanism for activation of phosphorylase in nerve tissue is similar to that in muscle.

Abstract

Abstract— Phosphorylase b kinase (ATP: phosphorylase phosphotransferase; EC 2.7.1.38), the enzyme which converts phosphorylase b to phosphorylase a (α‐1,4‐glucan: orthophosphate glucosyltransferase; EC2.4.1.1) was examined in nerve tissue. Both phosphorylase and phosphorylase kinase were present in all nerve tissues tested, with central tissues about ten times as active as peripheral nerve. Exceptions were the superior cervical and stellate ganglia, tissues rich in synapses, which displayed activity similar to brain. Phosphorylase kinase in brain had properties similar to those of the enzyme in skeletal and cardiac muscle; it was activated in vitro by ATP and adenosine 3′,5′‐monophosphate (cyclic AMP) and by Ca 2+ . Subconvulsive doses of insulin or of amphetamine administered to mice produced some activation of the enzyme. It is concluded that the mechanism for activation of phosphorylase in nerve tissue is similar to that in muscle.