Apr 29, 1983

Synergistic functions of phorbol ester and calcium in serotonin release from human platelets

Biochemical and Biophysical Research Communications
J YamanishiY Nishizuka


In human platelets, thrombin activates Ca2+-activated, phospholipid-dependent protein kinase (protein kinase C) and mobilizes Ca2+ concomitantly, whereas 12-O-tetradecanoylphorbol-13-acetate (TPA) may be intercalated into membranes and directly activates protein kinase C without mobilization of Ca2+ in sufficient quantities. A series of experiments with TPA and Ca2+-ionophore (A23187) indicates that activation of protein kinase C is a prerequisite requirement for release of serotonin, and that this enzyme activation and Ca2+ mobilization act synergistically to elicit a full cellular response. Both cyclic AMP and cyclic GMP inhibit activation of protein kinase C by prohibiting the signal-dependent breakdown of inositol phospholipid to produce diacyl-glycerol, but none of these cyclic nucleotides prevents the TPA-induced activation of this enzyme.

  • References6
  • Citations136

Mentioned in this Paper

Tetradecanoylphorbol Acetate, 4a alpha-Isomer
Drug Augmentation
Phorbol Diesters
In Vitro [Publication Type]

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