title: Insulin stimulation of phospholipid methylation in isolated rat adipocyte plasma membranes.
abstract: Partially purified plasma membranes prepared from rat adipocytes contain N-methyltransferase(s) that utilize(s) S-adenosyl-L-methionine to synthesize phosphatidylcholine from phosphatidylethanolamine. The incorporation of [3H]methyl from S-adenosyl-L-[methyl-3H]methionine into plasma membrane phospholipids was linear with incubation time and plasma membrane protein concentration and was inhibited in a dose-dependent manner by both S-adenosyl-L-homocysteine and 3-deazadenosine. The addition of insulin to plasma membranes stimulated the methylation of endogenous phosphatidylethanolamine, as evidenced by an increase in the levels of phosphatidyl-N-monomethylethanolamine, phosphatidyl-N, N-dimethylethanolamine, and phosphatidylcholine. The effect of insulin was rapid and concentration-dependent, with 100 microunits/ml providing near maximal stimulation. The incorporation of [3H]methyl into phospholipids of control and insulin-stimulated plasma membranes was enhanced by the addition of exogenous methyltransferase substrates phosphatidylethanolamine, phosphatidyl-N-monomethylethanolamine, and phosphatidyl-N,N-dimethylethanolamine. The stimulatory effect of insulin on adipocyte plasma membrane phospholipid methylation may have a physiological role in insulin action.
mesh_terms: D000273:Adipose Tissue / Q000187:drug effects / Q000378:metabolism*; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism; D007328:Insulin / Q000494:pharmacology*; D007700:Kinetics; D008297:Male; D008563:Membrane Lipids / Q000378:metabolism*; D008745:Methylation; D008780:Methyltransferases / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D012436:S-Adenosylmethionine / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D007328:Insulin; D008563:Membrane Lipids; D010743:Phospholipids; D012436:S-Adenosylmethionine; D008780:Methyltransferases