Structure and function of cyclic nucleotide-dependent protein kinases.

Abstract

Cyclic AMP-dependent protein kinase (cAK) was first described in 19631964 (43, 132) as a cAMP-dependent glycogen synthase kinase that, in the presence of Mg/ A TP, transferred the 'V-phosphate of A TP to serines or threonines on many cellular enzymes. It was found to phosphorylate a number of proteins and was permanently named in 1968 (168). Ensuing years produced vast numbers of reports regarding properties of cAK and the signal mechanisms that elicit its activation. Many of these have been reviewed recently (8, 33,47, 85, 141, 155, 181). In 1970 cyclic GMP-de­ pendent protein kinase (cGK) was discovered (86). cGK is homologous in structure and function to cAK (24, 49, 59, 66, 93, 141, 154). The role of cGMP in physiological processes is increasingly appreciated (15, 39, 92, 94, 113, 170), but cGK is only one of several intracellular receptors for cGMP. Studies of the heterogeneity, function, and regulation of cAK and cGK have provided insight into the enzymology of diverse protein kinases and into the roles of these kinases in cellular processes.