title: Chloroplast ribonucleoproteins (RNPs) as phosphate acceptors for casein kinase II: purification by ssDNA-cellulose column chromatography.
abstract: Using ssDNA-cellulose column chromatography, a 34 kDa ribonucleoprotein (p34) has been purified from a 0.4 M KCl crude extract of spinach chloroplasts as an effective phosphate acceptor for casein kinase II (CK-II) in vitro. Monomeric and oligomeric CK-IIs were copurified with p34 by the column chromatography and the kinases were separated from p34 by means of Mono Q column chromatography. It was found that (i) the purified p34 (pI 4.9) was phosphorylated specifically by CK-II in vitro; and (ii) similar polypeptides, such as p35 (pI 4.7) and p39 (pI 4.9) in maize and p33 (pI 4.7) in liverwort, were detected as ssDNA-binding chloroplast proteins phosphorylated by CK-II in vitro. The findings suggest that (i) RNPs that function as phosphate acceptors for CK-II exist commonly in chloroplasts among plant cells; and (ii) the physiological activity of RNPs is regulated by their specific phosphorylation by CK-II in chloroplasts.
authors.affiliation: Laboratory of Biology, School of Liberal Arts and Sciences, Kitasato University, Sagamihara, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Kanekatsu
authors.forename: A
authors.initials: A
authors.lastname: Ezumi
authors.forename: T
authors.initials: T
authors.lastname: Nakamura
authors.forename: K
authors.initials: K
authors.lastname: Ohtsuki
mesh_terms: D047390:Casein Kinase II; D002736:Chloroplasts / Q000737:chemistry; D002847:Chromatography, Agarose; D004277:DNA, Single-Stranded / Q000737:chemistry; D010455:Peptides / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism*; D010766:Phosphorylation; D010940:Plant Proteins / Q000302:isolation & purification / Q000378:metabolism*; D010944:Plants / Q000737:chemistry; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D012261:Ribonucleoproteins / Q000302:isolation & purification / Q000378:metabolism*; D018724:Spinacia oleracea / Q000737:chemistry; D013379:Substrate Specificity; D003313:Zea mays / Q000737:chemistry
chemical_list: D004277:DNA, Single-Stranded; D010455:Peptides; D010710:Phosphates; D010940:Plant Proteins; D012261:Ribonucleoproteins; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases