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

Junji Yamanishi, Yoshimi Takai, Kozo Kaibuchi, Kimihiko Sano, Monique Castagna, Yasutomi Nishizuka

Research output: Contribution to journalArticlepeer-review

236 Citations (Scopus)


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 diacylglycerol, but none of these cyclic nucleotides prevents the TPA-induced activation of this enzyme.

Original languageEnglish
Pages (from-to)778-786
Number of pages9
JournalBiochemical and Biophysical Research Communications
Issue number2
Publication statusPublished - 29-04-1983
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biophysics
  • Biochemistry
  • Molecular Biology
  • Cell Biology


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