Phospholipid degradation in rat calcium ionophore-activated platelets is catalyzed mainly by two discrete secretory phospholipase As.

K Yokoyama, I Kudo, K Inoue

Faculty of Pharmaceutical Sciences, University of Tokyo.

Journal of biochemistry 1995 Jun

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An "A1 type" phospholipase activity with serine-phospholipid preference was released by rat activated platelets. It was distinct from the secretory type II phospholipase A2 [Horigome, K., Hayakawa, M., Inoue, K., and Nojima, S. (1987) J. Biochem. 101, 625-631] and co-purified with the secretory lysophosphatidylserine-selective lysophospholipase activity [Higashi, S., Kobayashi, T., Kudo, I., and Inoue, K. (1988) J. Biochem. 103, 442-447]. Several lines of evidence indicated that a single protein was responsible for the phospholipase A1 and lysophospholipase activities. Marked accumulation of lysophospholipids was observed in rat calcium ionophore-activated washed platelets and both phospholipase A1/lysophospholipase and type II phospholipase A2 were shown to contribute to this phospholipid degradation. A selective inhibitor of type II phospholipase A2 reduced the phospholipid degradation and enhanced the clotting time and prothrombinase activity. These results indicate that secretory platelet phospholipases may play a role in regulation of blood clotting.

Citation

K Yokoyama, I Kudo, K Inoue. Phospholipid degradation in rat calcium ionophore-activated platelets is catalyzed mainly by two discrete secretory phospholipase As. Journal of biochemistry. 1995 Jun;117(6):1280-7