Phospholipid degradation in rat calcium ionophore-activated platelets is catalyzed mainly by two discrete secretory phospholipase As.
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.
D000818:Animals; D001777:Blood Coagulation; D001792:Blood Platelets / Q000378:metabolism*; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D004229:Dithiothreitol / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005227:Fatty Acids / Q000032:analysis; D006863:Hydrogen-Ion Concentration; D007476:Ionophores / Q000494:pharmacology; D007531:Isoflurophate / Q000494:pharmacology; D007770:L-Lactate Dehydrogenase / Q000097:blood; D008245:Lysophospholipase / Q000097:blood / Q000302:isolation & purification; D008246:Lysophospholipids / Q000378:metabolism; D010741:Phospholipases A / Q000097:blood* / Q000302:isolation & purification; D054466:Phospholipases A1; D054467:Phospholipases A2; D010743:Phospholipids / Q000378:metabolism*; D015539:Platelet Activation; D051381:Rats; D013917:Thrombin / Q000494:pharmacology; D014966:Xanthenes / Q000494:pharmacology
D004791:Enzyme Inhibitors; D005227:Fatty Acids; D007476:Ionophores; D008246:Lysophospholipids; D010743:Phospholipids; D014966:Xanthenes; D007531:Isoflurophate; C072737:thielocin A1alpha; D000001:Calcimycin; D007770:L-Lactate Dehydrogenase; D010741:Phospholipases A; D054466:Phospholipases A1; D054467:Phospholipases A2; D008245:Lysophospholipase; D013917:Thrombin; D002118:Calcium; D004229:Dithiothreitol