Activation of protein kinase isoenzymes under near physiological conditions

[摘要]

cAMP-dependent protein kinase I and II (cAKI and cAKII) were incubated under near physiological conditions in the presence of various concentrations of 8-N₃-c[³H]AMP or c[³H]AMP. Both types (A and B) of cyclic nucleotide binding sites of cAKI or cAKII were occupied to a similar extent and the degree of their occupation correlated with the degree of kinase activation. cAKI cAKII bound cAMP in an apparent positively cooperative manner in the presence of Mg²⁺, ATP. 8-N₃-c[³H]AMP dissociated several orders of magnitude faster from site A than site B of the regulatory moeity of cAKII, and was photo-incorporated only when bound to site B.

[学科分类] 生物化学/生物物理

[关键词] cAMP-dependent protein kinase;Protein kinase isoenzymes;cAMP binding sites;Cooperative binding;of cAMP;8-azido-cAMP Affinity-labelling