Stimulation of fatty acid methylation in human red cell membranes by phospholipase A2 activation.
Nonpolar methylated products comprise approximately 50% of the radioactive material extractable into chloroform/methanol after incubation of human red cell membranes with S-[methyl-3H]adenosylmethionine. One of these nonpolar products is fatty acid methyl ester. The enzyme which synthesizes fatty acid methyl ester had an apparent Km for S-adenosylmethionine of about 0.6 micro M and a Vmax of about 0.6 pmol/mg protein per 30 min. Half-maximal activity was achieved upon addition of about 20 micro M sodium oleate. Of the fatty acids tested, sodium oleate increased activity most effectively (6-fold) and arachidonic acid was ineffective. Evidence indicated that fatty acid methylation takes place on the cytoplasmic side of the plasma membrane. The reaction was demonstrable in intact cells incubated with [methyl-3H]methionine, and increased upon addition of sodium oleate. Incubation of intact cells with melittin, a potent membrane phospholipase A2 activator from bee venom, increased fatty acid methylation several-fold. Fatty acid methylation appears to be one of the consequences of phospholipase A2 action in plasma membranes.
D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004910:Erythrocyte Membrane / Q000201:enzymology*; D004912:Erythrocytes / Q000201:enzymology*; D005227:Fatty Acids / Q000097:blood*; D006801:Humans; D008168:Lung / Q000378:metabolism; D008555:Melitten / Q000494:pharmacology; D008715:Methionine / Q000378:metabolism; D008745:Methylation; D019301:Oleic Acid; D009829:Oleic Acids / Q000096:biosynthesis / Q000494:pharmacology; D010740:Phospholipases / Q000097:blood*; D010741:Phospholipases A / Q000097:blood*; D054467:Phospholipases A2; D012436:S-Adenosylmethionine / Q000378:metabolism; D013379:Substrate Specificity
D005227:Fatty Acids; D009829:Oleic Acids; D008555:Melitten; D019301:Oleic Acid; C005576:methyl oleate; C013173:osteum; D012436:S-Adenosylmethionine; D008715:Methionine; D010740:Phospholipases; D010741:Phospholipases A; D054467:Phospholipases A2