Discrete interactions between phosphatidylethanolamine-N-methylation and phosphatidylinositolbisphosphate hydrolysis in rat myocardium.
Both phosphatidylethanolamine(PE)-N-methylation and phosphatidyl-inositol bisphosphate (PI-bisphosphate) breakdown potentially modify the microdomains in the sarcolemmal lipid bilayer. In this study the possibility of a mutual interaction between the enzymes responsible for these phospholipid reactions is examined. In sarcolemma purified from rat heart, prior hydrolysis of PI lipids by exogenous specific phospholipase C inhibited (to 75, 59 and 78% of control for sites I, II and II, respectively) the PE-N-methyltransferase system. In cultured rat cardiomyocytes the addition of L-methionine, a precursor for the methyl donor S-adenosylmethionine, stimulated PE-N-methylation in a concentration (0.2-300 microM)-dependent manner. Methionine (50 microM) decreased the basal rate of PI-bisphosphate hydrolysis (to 72% of control), but had no effect on the phenylephrine-stimulated PI-bisphosphate hydrolysis. Maximal activation of the PI-bisphosphate breakdown by 30 microM phenylephrine did not affect the rate of PE-N-methylation in the presence of exogenous methionine (50 microM). These findings support the existence of interactions, although discrete, between the enzymes involved in the PE-N-methylation and PI turnover.
Meij
J T
JT
Department of Biochemistry I, Erasmus University Rotterdam, The Netherlands.
Paolillo
G
G
Bezstarosti
K
K
Verdouw
P D
PD
Panagia
V
V
Lamers
J M
JM
D000322:Adrenergic Agonists / Q000494:pharmacology; D000818:Animals; D002478:Cells, Cultured; D006868:Hydrolysis / Q000187:drug effects; D008745:Methylation; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D010714:Phosphatidylethanolamines / Q000378:metabolism*; D010716:Phosphatidylinositols / Q000378:metabolism*; D051381:Rats; D012436:S-Adenosylmethionine / Q000493:pharmacokinetics; D012508:Sarcolemma; D010738:Type C Phospholipases / Q000493:pharmacokinetics
D000322:Adrenergic Agonists; D010714:Phosphatidylethanolamines; D010716:Phosphatidylinositols; D012436:S-Adenosylmethionine; D010738:Type C Phospholipases