Ca(2+)-sensor region of IP(3) receptor controls intracellular Ca(2+) signaling

EMBO J. 2001 Apr 2;20(7):1674-80. doi: 10.1093/emboj/20.7.1674.


Many important cell functions are controlled by Ca(2+) release from intracellular stores via the inositol 1,4,5-trisphosphate receptor (IP(3)R), which requires both IP(3) and Ca(2+) for its activity. Due to the Ca(2+) requirement, the IP(3)R and the cytoplasmic Ca(2+) concentration form a positive feedback loop, which has been assumed to confer regenerativity on the IP(3)-induced Ca(2+) release and to play an important role in the generation of spatiotemporal patterns of Ca(2+) signals such as Ca(2+) waves and oscillations. Here we show that glutamate 2100 of rat type 1 IP(3)R (IP(3)R1) is a key residue for the Ca(2+) requirement. Substitution of this residue by aspartate (E2100D) results in a 10-fold decrease in the Ca(2+) sensitivity without other effects on the properties of the IP(3)R1. Agonist-induced Ca(2+) responses are greatly diminished in cells expressing the E2100D mutant IP(3)R1, particularly the rate of rise of initial Ca(2+) spike is markedly reduced and the subsequent Ca(2+) oscillations are abolished. These results demonstrate that the Ca(2+) sensitivity of the IP(3)R is functionally indispensable for the determination of Ca(2+) signaling patterns.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenosine Triphosphate / metabolism
  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • Calcium / metabolism
  • Calcium Channels / genetics
  • Calcium Channels / metabolism*
  • Calcium Channels / physiology
  • Calcium Signaling / physiology*
  • Cell Membrane / metabolism
  • Chickens
  • Inositol 1,4,5-Trisphosphate / metabolism*
  • Inositol 1,4,5-Trisphosphate Receptors
  • Intracellular Fluid / metabolism
  • Microscopy, Fluorescence
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Rats
  • Receptors, Cytoplasmic and Nuclear / genetics
  • Receptors, Cytoplasmic and Nuclear / metabolism*
  • Receptors, Cytoplasmic and Nuclear / physiology
  • Tumor Cells, Cultured


  • Calcium Channels
  • Inositol 1,4,5-Trisphosphate Receptors
  • Receptors, Cytoplasmic and Nuclear
  • Inositol 1,4,5-Trisphosphate
  • Adenosine Triphosphate
  • Calcium