Metabolism of red-cell lipids : III. Pathways for phospholipid renewal

Abstract

1. 1. Experiments on the conversion of various phospholipid precursors by red-cell ghosts indicated that monoacyl phosphoglycerides are the major acyl acceptors involved in the fatty acid incorporation into lipids of mature mammalian erythrocytes.

2. 2. Lysates of red cells were incapable of catalyzing the hydrolysis of lecithin into the monoacyl derivative. Lysolecithin derived from the plasma by an exchange reaction was found to be acylated to some extent by intact erythrocytes so as to form lecithin.

3. 3. The renewal of phospholipids from erythrocytes is considered to involve at least two processes: (a) exchange of phospholipid molecules between serum and cells, (b) a positionally specific incorporation of saturated and unsaturated fatty acids with the participation of monoacyl phosphoglycerides originating from the serum.

4. 4. The extent of these processes was found to be different for distinct classes of phospholipids, while even within one phospholipid class not all molecular species participated in the exchange reaction. The magnitude of phospholipid renewal appears to differ between erythrocytes of various mammalian species.