Calmodulin- and Ca2(+)-insensitive fatty acid methyltransferase from RINm5F cells. Inhibition by trifluoperazine and W7.
1. Methylation of endogenous lipids by homogenates of rat insulinoma cells was studied. 2. 3H-methyl groups (38 pmol/mg protein per 10 min) from [3H-methyl]S-adenosyl-L-methionine were incorporated into endogenous lipids, mainly (greater than 80%) into the neutral lipid fraction. 3. The reaction was sensitive to heat, was almost abolished by S-adenosyl-L-homocysteine, but insensitive to the addition of EGTA (5 mM), Ca2+ (5-100 microM) and/or calmodulin (15 microns). 4. At concentrations relevant for calmodulin antagonistic activity strong inhibition by W7 and trifluoperazine (25-100 microM each), but not by CGS 9343B (10 microM), was observed. 5. Calmodulin antagonists of phenothiazine- and sulfonamide-type appear to block the fatty acid methyltransferase in a way unrelated to calmodulin.
Safayhi
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Department of Pharmacology, University of Tübingen, Germany.
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D000818:Animals; D001562:Benzimidazoles / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D004533:Egtazic Acid / Q000494:pharmacology; D006358:Hot Temperature; D007340:Insulinoma / Q000201:enzymology*; D008745:Methylation; D008780:Methyltransferases / Q000037:antagonists & inhibitors*; D010190:Pancreatic Neoplasms / Q000201:enzymology*; D051381:Rats; D012435:S-Adenosylhomocysteine / Q000494:pharmacology; D013449:Sulfonamides / Q000494:pharmacology*; D014268:Trifluoperazine / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D001562:Benzimidazoles; D002147:Calmodulin; D013449:Sulfonamides; C052087:CGS 9343B; D014268:Trifluoperazine; D004533:Egtazic Acid; C017967:W 7; D012435:S-Adenosylhomocysteine; D008780:Methyltransferases; C070107:fatty acid methyltransferase; D002118:Calcium