A non-histone chromatin protein that is a specific phosphate acceptor of nuclear cAMP-independent protein kinase from mouse spleen cells.
A non-histone chromatin protein (NHCP), which is specifically phosphorylated by a nuclear cAMP-independent protein kinase from mouse spleen cells in vitro, has been purified from calf thymus chromatin. SDS-polyacrylamide gel electrophoresis shows that the molecular weight of the purified NHCP (single peptide) is 13,000. This peptide consists of 14 amino acid residues and has high serine content (17.9%). However, no methionine, proline, or half-cysteine have been detected. The NHCP is a basic protein (isoelectric point, approximately 9.0), although it has high acidic amino acid content (26.2%). This protein serves as the most effective phosphate acceptor for the kinase in vitro when compared with other chromatin proteins such as histones; the Km value of the kinase for the NHCP is 3.65 x 10(-6) M, whereas that for histone H2a (Mr = 14,000) is 1.08 x 10(-5) M. The present finding that the NHCP phosphorylation by the kinase in vitro is remarkably stimulated by double-stranded DNA but inhibited by whole histone or histone H2a suggests that the phosphorylation may be controlled by both double-stranded DNA and histone H2a.
D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002417:Cattle; D002467:Cell Nucleus / Q000201:enzymology*; D002868:Chromosomal Proteins, Non-Histone / Q000378:metabolism*; D000242:Cyclic AMP / Q000494:pharmacology; D006657:Histones; D007700:Kinetics; D051379:Mice; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D013154:Spleen / Q000201:enzymology*; D013379:Substrate Specificity; D013950:Thymus Gland
D000596:Amino Acids; D002868:Chromosomal Proteins, Non-Histone; D006657:Histones; D000242:Cyclic AMP; D011494:Protein Kinases