Role of protein kinase CK2 in phosphorylation of nucleosomal proteins in relation to transcriptional activity

Protein kinase CK2 undergoes rapid translocation to nuclear matrix and nucl eosomes on androgenic stimulation of growth in prostatic epithelial cells. Further, CK2 appears to be regulated differentially in the transcriptionall y active and inactive nucleosomes. We have investigated the role of CK2 in phosphorylation of nucleosome-associated proteins in the transcriptionally active and inactive nucleosomes that were isolated from ventral prostate su bjected to different androgenic status in vivo. Proteins associated with th ese nucleosomes were phosphorylated via the intrinsic protein kinase activi ty, using [gamma-P-32]ATP in the absence and presence of GTP. Several prote ins appear to be potential substrates for CK2 associated with the nucleosom es. Among them are proteins that are differentially associated with the tra nscriptionally active and inactive nucleosomes. Phosphorylation of several of these proteins is modulated depending not only on their sites of associa tion (i.e., active vs. inactive nucleosomes) but also on the state of trans criptional activity. Differential phosphorylation of specific proteins by C K2 associated with the active and inactive nucleosomes may be pertinent to the process of transcription regulation.