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Characterization of Brain Synaptic Vesicle Phospholipase A 2 Activity and Its Modulation by Calmodulin, Prostaglandin E 2 , Prostaglandin F 2α , Cyclic AMP, and ATP
Author(s) -
Moskowitz Nathan,
Puszkin Saul,
Schook William
Publication year - 1983
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1983.tb00867.x
Subject(s) - synaptic vesicle , vesicle , calmodulin , phospholipase a2 , prostaglandin , neurotransmitter , prostaglandin e , chemistry , biophysics , kiss and run fusion , enzyme , biochemistry , biology , receptor , membrane
Brain synaptic vesicle phospholipase A 2 (PLA 2 ) activity was characterized. It is Ca 2+ ‐dependent and has a pH optimum of 9.0. The enzyme has a K m of 60 μ M and a V max of 2.0 nmol/mg/h. Calmodulin, prostaglandin F 2α , and cAMP, and ATP all increased the V max of the enzyme. Prostaglandin E 2 inhibited the V max in the presence or absence of calmodulin. Light‐scattering techniques in conjunction with phase‐contrast and electron microscopy demonstrated that an increase in V max of PLA 2 was correlated with synaptic vesicle aggregation, lysis, and possible fusion. In vitro synaptic vesicle‐vesicle association that was stimulated by conditions that in creased PLA 2 activity could be diminished when synaptic vesicles were preincubated with PLA 2 inhibitors. It is suggested that endogenous synaptic vesicle PLA 2 activity may be an important mechanism underlying Ca 2+ ‐mediated neurotransmitter release.