PHOSPHOLIPID METHYLATION UNMASKS CRYPTIC BETA-ADRENERGIC RECEPTORS IN RAT RETICULOCYTES

The effect of phospholipid methylation on the number of β-adrenergic receptor binding sites was examined in rat reticulocyte membranes. Stimulation of phosphatidylcholine synthesis by the introduction of the methyl donor S-adenosyl-L-methionine into reticulocyte ghosts increased the number of β-adrenergic receptor binding sites. The appearance of β-adrenergic binding sites was dependent on the formation of phosphatidylcholine by the enzyme that converts phosphatidyl-N-monomethylethanolamine to phosphatidylcholine, but not on the synthesis of phosphatidyl-N- monomethylethanolamine from phosphatidylethanolamine. Both the synthesis of phosphatidylcholine and the unmasking of cryptic receptors were time and temperature dependent and did not occur in the presence of the methyl transferase inhibitor, S-adenosyl-L-homocysteine. Copyright © 1979 AAAS.