title: Guanosine 5'-triphosphate modulation of S-adenosyl-L-methionine-mediated methylation of phosphatidylethanolamine in rat liver plasma membrane.
abstract: Effect of guanosine 5'-triphosphate(GTP) on the S-adenosyl-L-methionine-mediated methylation of phosphatidylethanolamine was examined using rat liver plasma membranes. Methyltransferase I, which catalyzes methylation of phosphatidylethanolamine to phosphatidyl-N-mono-methylethanolamine was inhibited by GTP, whereas methyltransferase II, which transfers methyl groups from S-adenosyl-L-methionine to produce phosphatidyl-N,N-dimethylethanolamine or phosphatidyl-choline was stimulated by GTP. d,l-isoproterenol stimulated methyl-transferase II activity slightly. This stimulation was greatly augmented by GTP. d,l-isoproterenol inhibited methyltransferase I and this inhibition was enhanced by GTP. The results indicate that GTP has a regulatory role in the methylation of phospholipids in the plasma membrane through inactivation of methyltransferase I and activation of methyltransferase II by binding to these enzymes.
mesh_terms: D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D000242:Cyclic AMP / Q000494:pharmacology; D006160:Guanosine Triphosphate / Q000494:pharmacology*; D007545:Isoproterenol / Q000494:pharmacology; D007700:Kinetics; D008099:Liver / Q000378:metabolism*; D008297:Male; D008780:Methyltransferases / Q000378:metabolism*; D050918:Phosphatidylethanolamine N-Methyltransferase; D010714:Phosphatidylethanolamines / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012436:S-Adenosylmethionine / Q000378:metabolism*; D013806:Theophylline / Q000494:pharmacology
chemical_list: D010714:Phosphatidylethanolamines; D012436:S-Adenosylmethionine; D006160:Guanosine Triphosphate; D013806:Theophylline; D000242:Cyclic AMP; D008780:Methyltransferases; D050918:Phosphatidylethanolamine N-Methyltransferase; D007545:Isoproterenol