Calreticulin modulates capacitative Ca2+ influx by controlling the extent of inositol 1,4,5-trisphosphate-induced Ca2+ store depletion

Wen Xu, Frank J. Longo, Mary R. Wintermantel, Xueying Jiang, Robert A. Clark, Sylvain DeLisle

Research output: Contribution to journalArticle

44 Scopus citations

Abstract

Calreticulin (CRT) is a highly conserved Ca2+-binding protein that resides in the lumen of the endoplasmic reticulum (ER). We overexpressed CRT in Xenopus oocytes to determine how it could modulate inositol 1,4,5-trisphosphate (InsP3)-induced Ca2+ influx. Under conditions where it did not affect the spatially complex elevations in free cytosolic Ca2+ concentration ([Ca2+](i)) due to InsP3-induced Ca2+ release, overexpressed CRT decreased by 46% the Ca2+-gated Cl- current due to Ca2+ influx. Deletion mutants revealed that CRT requires its high capacity Ca2+-binding domain to reduce the elevations of [Ca2+](i) due to Ca2+ influx. This functional domain was also required for CRT to attenuate the InsP3-induced decline in the free Ca2+ concentration within the ER lumen ([Ca2+](ER)), as monitored with a 'chameleon' indicator. Our data suggest that by buffering [Ca2+](ER) near resting levels, CRT may prevent InsP3 from depleting the intracellular stores sufficiently to activate Ca2+ influx.

Original languageEnglish (US)
Pages (from-to)36676-36682
Number of pages7
JournalJournal of Biological Chemistry
Volume275
Issue number47
DOIs
StatePublished - Nov 24 2000

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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