Phospholipase activity and plasma membrane homeostasis.

Cyclic changes in the physiochemical state of the plasma membrane appear to be necessary for the normal functioning of the cell, especially with respect to division and differentiation. Such changes require a flexible membrane lipid composition to permit the necessary sequence of physicochemical changes to occur during these cellular events. This flexibility can be lost as a result of peroxidation-induced cross linking of membrane constituents, which prevents the normal physico-chemical membrane changes from occurring, resulting in abnormal cellular function. It is proposed that phospholipase A2 and C form a mutually regulatory enzyme system playing an important role with respect to the maintenance of membrane composition and flexibility.