Purification of a low molecular weight non-histone chromosomal protein

Biochemical characterization of a specific phosphate acceptor of nuclear cyclic AMP-independent protein kinase

The regulatory mechanism of transcription involved in the phosphorylation of a 13 kDa non-histone chromatin protein from calf thymus, which is the most effective phosphate acceptor for cyclic AMP-independent protein kinase purified from the nuclei of mouse spleen cells, by the kinase has been studied in vitro. An analytical study of the circular dichroism (CD) spectra of the 13 kDa protein under different conditions showed that it underwent a major conformational change when incubated with DNA. The presented data suggest that the DNA-induced conformational change may result in a great increase of the 13 kDa protein phosphorylation by the kinase in vitro. Mg2+ (8-10 mM) enhanced the binding of the protein to DNA. Furthermore, the phosphorylated 13 kDa protein stimulated elongation of RNA synthesis by RNA polymerase II from calf thymus. However, neither the 13 kDa protein nor the phosphorylated 13 kDa protein had any affect on DNA synthesis. The available evidence suggests that the 13 kDa protein may play a role in the regulation of transcription through its phosphorylation by the kinase in vitro.

Evidence of the mannosylation of a non-histone protein in monkey liver chromatin

Mannose is incorporated in monkey liver chromatin by the means of a nuclear membrane mannosyltransferase. 14C-labelled chromatin is dissociated either by sulfuric acid or 6 M urea and 0.4 M GuCl. The fractions then enriched in non-histone 14C-labelled proteins are excluded from Ultro-gel AcA 202, their analysis in SDS-polyacrylamide gel electrophoresis shows that radioactivity fits with one major protein band, confirming the presence of at least a non-histone protein labelled with mannose in monkey liver chromatin, with an apparent molecular weight of 13,000.

The loosely bound non-histone chromosomal proteins of rat prostate in androgen action

Rat prostatic chromatin was fractionated by sequential salt extractions into 0.35 M NaCl-soluble (the loosely bound non-histone chromosomal proteins), 2 M NaCl-soluble and -insoluble (the residual proteins) fractions. Homologous and heterologous chromatins were reconstituted with these chromosomal fractions from castrated rats injected with testosterone for 2 h and from castrated control. Chromatin reconstituted with all hormone-treated fractions showed 30% more binding with polylysine and transcriptional template activity than did chromatin reconstituted with castrated fractions. Similar analyses of reconstituted heterologous chromatins indicated that the androgen-induced changes in chromatin were mainly determined by the androgenic state of the 0.35 M NaCl-soluble fraction. The 0.35 M NaCl-soluble fraction also contained 18% more total high mobility group protein than did the corresponding castrated fraction. Limited digestion of 5 alpha-[3H]dihydrotestosterone-bound nuclei with pancreatic DNAase 1 to 5% acid-soluble resulted in a rapid release of the nuclear-bound 3H-labelled androgen and protein, in contrast to similar digestion with microsomal nuclease. Since a large portion of the translocation androgen-receptor is bound to protein(s) in the 0.35 M NaCl-soluble fraction, these results suggest that the component(s) in the 0.35 M NaCl-soluble fraction to which androgen-receptor binds is associated with actively transcribing sequences on chromatin.