NOVEL HIGHLY SPECIFIC AND POTENT INHIBITOR OF CALMODULIN-DEPENDENT PROTEIN-KINASE-II

A novel synthetic peptide AIP autocamtide-2-related inhibitory peptide), a nonphosphorylatable analog of autocamtide-2, was found to be a highly specific and potent inhibitor of calmodulin-dependent protein kinase II (CaM-kinase II). It was 50 and 500 times more potent than CaMK-(281-302A1a286) and KN-93, respectively, under the assay conditions used. The inhibition was unaffected by the presence or absence of Ca2+/calmodulin, and it was competitive with autocamtide-2 and noncompetitive with syntide-2. AIP (1 mu M) completely inhibited CaM-kinase II activity, but did not affect cyclic AMP-dependent protein kinase, protein kinase C, calmodulin-dependent protein kinase IV, and unidentified protein kinases occurring in a rat brain extract. These results indicate that AIP is a useful tool for studying the physiological roles of CaM-kinase II. (C) 1995 Academic Press, Inc.