Coenzyme A independent acylation of phosphatidylethanolamine in isolated bovine rod cell outer segments.
The acylation of membrane phospholipids in isolated bovine rod outer segments (ROS) by exogenous, radiolabeled palmitic acid (16:0) was assayed, using [14C]palmitoyl-coenzyme A (16:0-CoA), [3H]16:0 alone and [3H]16:0 with added ATP and CoA. Both [14C]16:0-CoA and [3H]16:0 with added ATP and CoA are incorporated predominantly into phosphatidylcholine (PC), whereas [3H]16:0 without added ATP and CoA is incorporated almost exclusively into phosphatidylethanolamine (PE). Without added ATP and CoA in the incubation medium, [3H]16:0 is esterified predominantly to the 2 position of PE, but with added ATP and CoA, it is esterified to both the 1 and 2 positions; the rates of esterification of [3H]16:0 to the 2 position of PE under these two conditions are similar. These results suggest that 16:0 is esterified to the 2 position of PE of ROS membranes by an acyl transferase mechanism that does not utilize an acyl-CoA intermediate. The product of this reaction is likely to be a molecular species of PE with 16:0 at the 2 position and a polyunsaturated fatty acid at the 1 position.
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Biology Department, Amherst College, MA 01002.
Zimmerman
W F
WF
D000217:Acyltransferases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002417:Cattle; D003065:Coenzyme A / Q000378:metabolism*; D066298:In Vitro Techniques; D010169:Palmitic Acids / Q000378:metabolism; D010171:Palmitoyl Coenzyme A / Q000378:metabolism; D010713:Phosphatidylcholines / Q000096:biosynthesis; D010714:Phosphatidylethanolamines / Q000096:biosynthesis*; D012374:Rod Cell Outer Segment / Q000201:enzymology*; D013997:Time Factors
D010169:Palmitic Acids; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; D010171:Palmitoyl Coenzyme A; D000255:Adenosine Triphosphate; D000217:Acyltransferases; D003065:Coenzyme A