Inhibitory effects of cyclic-AMP dependent protein kinase on guanylate cyclase activity in rat cerebellum

Abstract

Guanylate cyclase (EC 4.6.1.2) the enzyme responsible for the formation of cyclic GMP from GTP, has been studied in homogenates or both supernatant and particulate fractions of several tissues [l-8]. Recently, various authors suggested that soluble and particulate guanylate cyclase have different kinetic properties and molecular size [9-l I] , and that the different forms of the enzyme may be independently regulated. Nevertheless, the regulatory mechanisms of guanylate cyclase activity remain unclear, although the importance of Ca2+ has been demonstrated in many tissues [12-l 51. In the present study we observed an inhibitory effect of 3’,5’cyclic adenosine monophosphate (cyclic AMP) dependent protein kinase (ATP, protein phosphotransferase (EC 2.7.1.37)) on guanylate cyclase activity in rat cerebellar homogenates. A possible regulatory mechanism of guanylate cyclase is proposed.