These tools will no longer be maintained as of December 31, 2024. Archived website can be found here. PubMed4Hh GitHub repository can be found here. Contact NLM Customer Service if you have questions.


Pubmed for Handhelds

PUBMED FOR HANDHELDS

Search MEDLINE/PubMed

  • Title: Luminal Ca2+ increases the affinity of inositol 1,4,5-trisphosphate for its receptor.
    Author: Oldershaw KA, Taylor CW.
    Journal: Biochem J; 1993 Jun 15; 292 ( Pt 3)(Pt 3):631-3. PubMed ID: 8391254.
    Abstract:
    Luminal Ca2+ has been proposed to regulate the sensitivity of intracellular Ca2+ stores to InsP3 and perhaps thereby to contribute to the mechanisms responsible for regenerative intracellular Ca2+ signals. Since Ca2+ release from intracellular stores is accompanied by K+ influx into the stores, InsP3-stimulated Ca2+ mobilization can be inhibited by substantially reducing the [K+] of incubation media. By measuring [3H]InsP3 binding to permeabilized hepatocytes in K(+)-deficient media, thereby preventing InsP3-stimulated Ca2+ mobilization, we have examined the effects of Ca2+ within the intracellular stores on equilibrium binding of InsP3 to its receptor. Our results demonstrate a small, but significant (P < 0.05, n = 8-9), effect of luminal Ca2+ on InsP3 binding; the concentration of InsP3 causing half-maximal displacement of [3H]InsP3 (1.25 nM) was 3.5 nM for empty stores and 2.1 nM for stores containing Ca2+. Our results suggest that at least part of the stimulatory effect of luminal Ca2+ on InsP3-stimulated Ca2+ mobilization may result from an effect of luminal Ca2+ on InsP3 binding to its receptor.
    [Abstract] [Full Text] [Related] [New Search]