Phosphorylation of rat brain calmodulin in vivo and in vitro.
After injection of [32p]orthophosphate into the third ventricle of rat brain, calmodulin(CaM) was prepared from soluble(S2) and particulate(P2) fractions of the whole brain and analyzed by SDS-PAGE in the presence or absence of Ca2+ followed by autoradiography. CaM from both fractions(S2 and P2) was significantly phosphorylated by endogenous protein kinase(s) of rat brain. The incorporation of radioactive phosphate into membrane-bound CaM from the P2 fraction was much higher than that of soluble CaM from the S2 fraction. CaM was phosphorylated in vitro by casein kinase 2 but not by casein kinase 1 or by cyclic AMP-dependent protein kinase, suggesting that casein kinase 2 may be, at least in part, responsible for the phosphorylation of CaM even in vivo.
D000818:Animals; D001921:Brain / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D002552:Cerebral Ventricles / Q000378:metabolism*; D066298:In Vitro Techniques; D010710:Phosphates / Q000378:metabolism; D010761:Phosphorus Radioisotopes; D010766:Phosphorylation; D051381:Rats; D011919:Rats, Inbred Strains
D002147:Calmodulin; D010710:Phosphates; D010761:Phosphorus Radioisotopes