NUCLEAR CHROMATIN PROTEINS FROM RABBIT CEREBRUM, CEREBELLUM AND LIVER: SYNTHESIS AND PHOSPHORYLATION

Abstract

Abstract— In order to investigate synthesis and phosphorylation of the various fractions of nuclear proteins. [3H]leucine and [32P] phosphate incorporation were studied with tissue slices in vitro. Cerebral cortex and cerebellum were used to delineate the similarity and dissimilarity within CNS, and liver was taken to compare the extraneural organ. There were significant differences in [3H]leucine incorporation into nuclear proteins among those tissue sources examined, while [32P]phosphate incorporation showed very similar results among them. Although the acidic chromatin protein demonstrated high activity in each tissue source for both synthesis and phosphorylation, 0.14M‐NaCl soluble protein showed the activity as high as or even higher than the acidic chromatin protein. Both [3H]leucine incorporation and [32P]phosphate incorporation were relatively low in histone. When the acidic chromatin protein was further fractionated with SDS‐acrylamide gel electrophoresis, significant difference was found between CNS tissue and liver for synthesis and phosphorylation. However, considerable difference was also observed even between cerebral cortex and cerebellum. The present investigation demonstrated complicity and diversity of nuclear chromatin proteins in different organs, not only for their protein constituents but also for their synthesis and phosphorylation.