title: Immunologically and enzymatically distinct rat choline kinase isozymes.
abstract: The purification and characterization of choline kinase R1 expressed in Escherichia coli, using expression plasmid pKCK(H) constructed with rat liver choline kinase cDNA [Uchida, T. and Yamashita, S. (1992) J. Biol. Chem. 267, 10156-10162], were carried out. Choline kinase R1 was chromatographically, enzymatically, and immunologically distinct from rat brain choline kinase [Uchida, T. and Yamashita, S. (1990) Biochim. Biophys. Acta 1043, 281-288]. This report, for the first time, definitively demonstrates the presence of two types of choline kinase isozymes. Rat choline kinase was immunologically classified into choline kinases P and R. Choline kinase P was purified from rat brain as described previously. Choline kinase R was designated as the choline kinase generated from the choline kinase R gene for choline kinase R1. Choline kinases from cytosol were chromatographically separated into two fractions, that is, one passed through a Blue-Toyopearl column and the other was retained on it. The choline kinase retained on the Blue-Toyopearl column was highly purified from rat liver cytosol and characterized in this study, being found to comprise isoforms of choline kinase R, and a choline kinase which was immunologically similar to choline kinase P. Choline kinases P and R are co-distributed in rat tissues. The carcinogen, 3-methylcholanthrene, and hepatotoxic carbon tetrachloride increased the enzyme activity, and the transcript and protein levels of choline kinase R in rat liver. The relation of choline kinase isozymes to previously purified enzymes was discussed.
authors.affiliation: Department of Biochemistry, Gunma University School of Medicine.
authors.forename: T
authors.initials: T
authors.lastname: Uchida
mesh_terms: D000818:Animals; D000906:Antibodies; D001483:Base Sequence; D002251:Carbon Tetrachloride / Q000494:pharmacology; D002413:Cations, Divalent; D002797:Choline Kinase / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism*; D004790:Enzyme Induction; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D006863:Hydrogen-Ion Concentration; D007527:Isoenzymes / Q000276:immunology* / Q000302:isolation & purification / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000737:chemistry / Q000187:drug effects / Q000201:enzymology; D008297:Male; D008748:Methylcholanthrene / Q000494:pharmacology; D008969:Molecular Sequence Data; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D013379:Substrate Specificity; D014018:Tissue Distribution
chemical_list: D000906:Antibodies; D002413:Cations, Divalent; D007527:Isoenzymes; D011506:Proteins; D012333:RNA, Messenger; D008748:Methylcholanthrene; D002251:Carbon Tetrachloride; D002797:Choline Kinase