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STIM is a Ca2+ sensor essential for Ca2+-store-depletion-triggered Ca2+ influx.

Ca(2+) signaling in nonexcitable cells is typically initiated by receptor-triggered production of inositol-1,4,5-trisphosphate and the release of Ca(2+) from intracellular stores. An elusive signaling process senses the Ca(2+) store depletion and triggers the opening of plasma membrane Ca(2+) channels. The resulting sustained Ca(2+) signals are required for many physiological responses, such as T cell activation and differentiation. Here, we monitored receptor-triggered Ca(2+) signals in cells transfected with siRNAs against 2,304 human signaling proteins, and we identified two proteins required for Ca(2+)-store-depletion-mediated Ca(2+) influx, STIM1 and STIM2. These proteins have a single transmembrane region with a putative Ca(2+) binding domain in the lumen of the endoplasmic reticulum. Ca(2+) store depletion led to a rapid translocation of STIM1 into puncta that accumulated near the plasma membrane. Introducing a point mutation in the STIM1 Ca(2+) binding domain resulted in prelocalization of the protein in puncta, and this mutant failed to respond to store depletion. Our study suggests that STIM proteins function as Ca(2+) store sensors in the signaling pathway connecting Ca(2+) store depletion to Ca(2+) influx.

Pubmed ID: 16005298


  • Liou J
  • Kim ML
  • Heo WD
  • Jones JT
  • Myers JW
  • Ferrell JE
  • Meyer T


Current biology : CB

Publication Data

July 12, 2005

Associated Grants

  • Agency: NIGMS NIH HHS, Id: R01 GM030179
  • Agency: NIGMS NIH HHS, Id: R01 GM030179-24A1
  • Agency: NIGMS NIH HHS, Id: R01 GM030179-25

Mesh Terms

  • Calcium
  • Calcium Channels
  • Cell Adhesion Molecules
  • Endoplasmic Reticulum
  • Fluorescence
  • HeLa Cells
  • Humans
  • Intracellular Signaling Peptides and Proteins
  • Jurkat Cells
  • Membrane Proteins
  • Mutation
  • Neoplasm Proteins
  • RNA, Small Interfering
  • Signal Transduction