Phosphorylcholine is part of the platelet-activating factor; the phospholipid phosphatidylcholine and sphingomyelin, the only phospholipid of the membrane that is not built with a glycerol backbone.
Phosphorylcholine is a component of platelet-activating factor; phosphatidylcholine, a phospholipid, and sphingomyelin, the only phospholipid in the membrane that lacks a glycerol backbone, are also mentioned.