The apparent transfer of fatty acid from phosphatidylcholine to phosphatidylethanolamine in human erythrocytes

Abstract

In previous studies an apparent transfer of 14C-labeled fatty acid from phosphatidylcholine to phosphatidylethanolamine was observed in prelabeled human erythrocytes reincubated in fresh serum. These data could have been explained by direct fatty acid transfer from phosphatidylcholine to phosphatidylethanolamine or by an apparent transfer simulated by either demethylation of labeled phosphatidylcholine to phosphatidylethanolamine or base-exchange of phosphatidylcholine with ethanolamine.To explore these possibilities, RBC containing phosphatidylcholine doubly labeled with palmitic acid-9,10-3H and with choline-1,2-14C were prepared. Upon reincubation in fresh serum, incorporation of 3H (fatty acid) into phosphatidylethanolamine was observed without incorporation of 14C (choline). In similar experiments in which RBC labeled with 3H-labeled fatty acid alone were used, 14C-ethanolamine added to the incubation was not incorporated into the isolated phosphatidylethanolamine which again showed incorporation of the fatty acid-3H.The data indicate that direct transfer of fatty acid from phosphatidylcholine to phosphatidylethanolamine can occur in human erythrocytes incubated in fresh serum.

Keywords

• palmitic acid