In this study we demonstrate that: (1) although the major phospholipase A2 present in sheep platelets is activated by calcium ions, it can effectively catalyze hydrolysis of the sn-2 ester linkage in phospholipids in the absence of calcium: (2) expression of calcium-independent phospholipase A2 activity can be induced by NACl utilizing purified (but not crude) cytosolic enzyme; and (3) calcium-independent phospholipase A2 activity is regulated by a reconstitutable cytosolic protein. Collectively, these results underscore the fundamental catalytic differences between extracellular and intracellular calcium-dependent phospholipases A2 and demonstrate that calcium is sufficient, but not necessary, for the activation of this class of intracellular phospholipases A2.

Original languageEnglish
Pages (from-to)27-30
Number of pages4
JournalFEBS Letters
Issue number1
StatePublished - Jun 17 1991


  • Arachidonic acid
  • Calcium
  • Phospholipase A
  • Plasmalogen
  • Platelet


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