'Quantal' Ca2+ release and the control of Ca2+ entry by inositol phosphates--a possible mechanism

FEBS Lett. 1990 Apr 9;263(1):5-9. doi: 10.1016/0014-5793(90)80692-c.


The release of Ca2+ from intracellular stores by sub-optimal doses of inositol trisphosphate has been shown to be dose-related ('quantal'), and a simple model is proposed here to account for this phenomenon. It is suggested that there is a regulatory Ca2(+)-binding site on, or associated with, the luminal domain of the InsP3 receptor, which allosterically controls Ca2+ efflux, and the affinity for Ca2+ of that site is modulated by InsP3 binding to the cytoplasmic domain of the receptor; a similar mechanism applied to the ryanodine receptor might also explain some aspects of Ca2(+)-induced Ca2+ release. The stimulated entry of Ca2+ into a cell which occurs upon activation of inositide-linked receptors has been variously and confusingly proposed to be regulated by InsP3, InsP4, and/or a 'capacitative' Ca2+ pool; the mechanism of InsP3 receptor action suggested here is shown to lead to a potential reconciliation of all these conflicting proposals.

Publication types

  • Review

MeSH terms

  • Animals
  • Calcium / metabolism*
  • Cell Membrane / metabolism
  • Endoplasmic Reticulum / metabolism
  • Inositol Phosphates / metabolism*
  • Models, Biological*
  • Signal Transduction


  • Inositol Phosphates
  • Calcium