Identification of a calcium-binding protein as a calcium-dependent regulator of brain adenylate cyclase.

An activating factor of adenylate cyclase (EC 4.6.1.1) HAS BEEN OBTAINED FROM DETERGENT-DISPERSED PREPARATIONS OF PORCINE CEREBRAL CORTEX BY COLUMN CHROMATOGRAPHY ON ECTEOLA-cellulose. The factor was identified by acrylamide gel electrophoresis and by enzyme activation studies as the Ca2+-binding protein that regulates the activity of a brain cyclic nucleotide phosphodiesterase. This Ca2+-binding protein confers a Ca2+-dependent activation upon the adenylate cyclase, which is reversed by the subsequent addition of egta in excess of the free Ca2+. It is proposed that this Ca2+-dependent regulator controls enzymatic activities responsible for the synthesis of adenosine 3':5'-monophosphate and for the hydrolysis of guanosine 3':5'-monophosphate.