Regulation of endogenous calcium-dependent synaptic membrane phospholipase A 2

Abstract

Synaptic plasma membrane preparations from brain tissue have endogenous Ca 2+-dependent phospholipase A 2 activity. Characterization of this activity revealed that it was maximally active at 10 −7−10 −5 M Ca 2+ and pH 7.0. The enzyme had aK m of 62.0 μM and a V max of 98.0 nmol/mg/h. Calmodulin and prostaglandin F 2α stimulated phospholipase A 2 activity, whereas prostaglandin E 2, cyclic AMP and ATP were inhibitory. Addition of exogenous phospholipase A 2 to synaptic plasma membrane and synaptic vesicle preparations led to their disruption and/or lysis. We suggest that Ca 2+-dependent regulation of phospholipase A 2 activity may be required for synaptic vesicle and synaptic plasma membrane interaction.