The inositol trisphosphate receptor of Xenopus oocytes

J. B. Parys, I. Bezprozvanny

Research output: Contribution to journalReview article

40 Scopus citations

Abstract

Xenopus laevis oocytes (stages V and VI) are a widely used model system for the study of Ca2+ signaling. The properties of the Xenopus oocyte InsP3 receptor (InsP3R) are of paramount importance for our thinking about this system and for our efforts to model Ca2+ dynamics in the oocyte cytosol. The recent data regarding the molecular structure, the regulation and the functional properties of the Xenopus oocyte InsP3R are summarized in this review. The main properties of the Xenopus oocyte InsP3R are compared with the properties of the cerebellar InsP3R and are shown to be remarkably similar. The density of the InsP3R in Xenopus oocyte cytoplasm is estimated to a value between 1.1-4.1 × 1014 tetrameric InsP3Rs/I. The use of these numbers in a quantitative model of Ca2+ wave propagation leads to values of Ca2+ wave amplitude (0.8-1.5 μM Ca2+) and velocity of the wave propagation (12-24 μm/s) that are in excellent agreement with the values observed experimentally. The density of InsP3Rs in Purkinje cells of the cerebellum is estimated to be about 20,000-fold higher, but in other types of neurons and in peripheral tissues the InsP3R density is estimated to be of the same order of magnitude as, or up to 20-fold higher than, in Xenopus oocytes. The implications of differences in InsP3R density for Ca2+ signaling are discussed.

Original languageEnglish (US)
Pages (from-to)353-363
Number of pages11
JournalCell Calcium
Volume18
Issue number5
DOIs
StatePublished - Nov 1995

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ASJC Scopus subject areas

  • Physiology
  • Molecular Biology
  • Cell Biology

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