Demonstration of a specific [3H]INS(1,4,5)P3 binding site in rat heart sarcoplasmic reticulum

B Huisamen, R Mouton, L H Opie, A Lochner

Research output: Contribution to journalArticle (Academic Journal)peer-review


Previous studies have suggested that inositol(1,4,5)-trisphosphate (InsP3) might induce release of Ca2+ by sarcoplasmic reticulum (SR) vesicles isolated from heart muscle. In this study binding sites specific for InsP3 in isolated SR vesicles from heart muscle were demonstrated. Scatchard analysis of a binding isotherm indicated two binding sites, viz a high affinity site with a Kd = 20 nM and Bmax = 4.2 pmol/mg protein and a low affinity site with a Kd = 424 nM and Bmax = 31 pmol/mg protein. Specificity of binding was demonstrated by using structural analogues. In addition to the finding of binding sites for InsP3, this membrane preparation also demonstrated a possible binding site for InsP4.

Original languageEnglish
Pages (from-to)341-9
Number of pages9
JournalJournal of Molecular and Cellular Cardiology
Issue number3
Publication statusPublished - Mar 1994


  • Animals
  • Calcium/metabolism
  • Calcium Channels/analysis
  • Inositol 1,4,5-Trisphosphate/metabolism
  • Inositol 1,4,5-Trisphosphate Receptors
  • Male
  • Muscle Proteins/analysis
  • Myocardium/chemistry
  • Protein Binding
  • Rats
  • Rats, Wistar
  • Receptors, Cytoplasmic and Nuclear/analysis
  • Sarcoplasmic Reticulum/chemistry
  • Second Messenger Systems


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