HMG-14 - A PHYSIOLOGICAL SUBSTRATE FOR CASEIN KINASE-NII OF NEURONAL CHROMATIN

The in vivo effects of antifeins on casein kinase NII from rat brain n euronal chromatin have been investigated. Injection of antifeins into rats resulted in changes in the cAMP-independent phosphorylation of HM G 14 by casein kinase NII, No change in HMG 17 phosphorylation was fou nd. Casein kinase NII was isolated and purified from rat brain neurona l chromatin. It was established that casein kinase phosphorylates HMG 14 (but not HMG 17) from rat brain cells and calf thymus as effectivel y as do exogenous substrates-phosvitin and casein. The K-m values for HMG 14 and HMG 17 from brain cells are 5.1 and 180.5 mu M, respectivel y. Antifeins do not influence casein kinase NII when HMG 17, phosvitin , and casein are used as substrates. The phosphorylation of HMG 14 cha nges significantly under the influence of antifeins (10(-8)-10(-6) M). Both in vivo and in vitro, some antifeins increase, while others redu ce the phosphorylation of HMG 14 by casein kinase NII, This correlates with their effect on transcription and long-term memory. The role of casein kinase NII and its physiological substrates in regulation of ch romatin transcription is discussed.