title: Phospholipases of plasmic membranes of adipose tissue. Possible intermediaries for insulin action.
abstract: In the present investigation we have shown that cytoplasmic membranes of adipocytes contain A1 and A2 phospholipase activities which are optimal in a buffer with 5 mM Ca2+ (pH 8.5). Insulin enhances these activities within phosphatidylethanolamine. Insulin increases also the amount of free fatty acids in membranes. Rodbell and Blecher have already shown an insulin-like action of phospholipases towards the uptake of glucose and amino-acids by adipocytes. Shier and Asakawa have recently described that lysolecithin and unsaturated fatty acids can change nucleotide-cyclase activities of cytoplasmic membranes towards GTP and ATP; lysolecithins and Triton X 100 seem to react in an identical way. Results from these studies give new suggestions on insulin action; phospholipase activation changes membrane physiochemical properties inducing an increase of glucose carrier mobility and leading the membrane cyclase enzyme (s) towards GMP cyclic synthesis.
mesh_terms: D000273:Adipose Tissue / Q000201:enzymology*; D000818:Animals; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology*; D005230:Fatty Acids, Nonesterified / Q000032:analysis; D007328:Insulin / Q000494:pharmacology*; D008563:Membrane Lipids / Q000032:analysis; D010740:Phospholipases / Q000378:metabolism*; D013379:Substrate Specificity
chemical_list: D005230:Fatty Acids, Nonesterified; D007328:Insulin; D008563:Membrane Lipids; D010740:Phospholipases