title: Induction of betaine: homocysteine methyltransferase in some murine cells cultured in vitro.
abstract: Betaine when present in the culture medium could induce the activity of betaine: homocysteine methyltransferase (EC 2.1.1.5) in mouse L-cells, and leukemic L1210 cells, as well as in mouse embryo fibroblasts grown in vitro. We found this process to be time- and concentration-dependent. A persisting contact of the cells with betaine was indispensible for expressing and maintaining the enzyme activity. The treatment of cells with cycloheximide or actinomycin D abolished the process of induction. Methionine as well as homocysteine, when present either in the culture medium or in the reaction mixture, strongly depressed the activity of this enzyme. The L-cells with the induced betaine:homocysteine methyltransferase survived but did not multiply in the methionine-deficient medium, therefore, they did not become prototrophs with respect to methionine.
mesh_terms: D000818:Animals; D001622:Betaine / Q000096:biosynthesis / Q000494:pharmacology*; D050940:Betaine-Homocysteine S-Methyltransferase; D002460:Cell Line; D002478:Cells, Cultured; D006224:Cricetinae; D004790:Enzyme Induction; D005347:Fibroblasts / Q000201:enzymology; D006710:Homocysteine / Q000096:biosynthesis; D007700:Kinetics; D007739:L Cells / Q000201:enzymology; D007939:Leukemia L1210 / Q000201:enzymology; D008715:Methionine / Q000494:pharmacology; D008780:Methyltransferases / Q000096:biosynthesis*; D051379:Mice
chemical_list: D006710:Homocysteine; D001622:Betaine; D008715:Methionine; D008780:Methyltransferases; D050940:Betaine-Homocysteine S-Methyltransferase; C494549:Bhmt protein, mouse