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XB-ART-4240
EMBO J 2004 Jan 28;232:312-21. doi: 10.1038/sj.emboj.7600037.
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Regulation of InsP3 receptor activity by neuronal Ca2+-binding proteins.

Kasri NN , Holmes AM , Bultynck G , Parys JB , Bootman MD , Rietdorf K , Missiaen L , McDonald F , De Smedt H , Conway SJ , Holmes AB , Berridge MJ , Roderick HL .


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Inositol 1,4,5-trisphosphate receptors (InsP(3)Rs) were recently demonstrated to be activated independently of InsP(3) by a family of calmodulin (CaM)-like neuronal Ca(2+)-binding proteins (CaBPs). We investigated the interaction of both naturally occurring long and short CaBP1 isoforms with InsP(3)Rs, and their functional effects on InsP(3)R-evoked Ca(2+) signals. Using several experimental paradigms, including transient expression in COS cells, acute injection of recombinant protein into Xenopus oocytes and (45)Ca(2+) flux from permeabilised COS cells, we demonstrated that CaBPs decrease the sensitivity of InsP(3)-induced Ca(2+) release (IICR). In addition, we found a Ca(2+)-independent interaction between CaBP1 and the NH(2)-terminal 159 amino acids of the type 1 InsP(3)R. This interaction resulted in decreased InsP(3) binding to the receptor reminiscent of that observed for CaM. Unlike CaM, however, CaBPs do not inhibit ryanodine receptors, have a higher affinity for InsP(3)Rs and more potently inhibited IICR. We also show that phosphorylation of CaBP1 at a casein kinase 2 consensus site regulates its inhibition of IICR. Our data suggest that CaBPs are endogenous regulators of InsP(3)Rs tuning the sensitivity of cells to InsP(3).

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Species referenced: Xenopus laevis
Genes referenced: cabp1

References [+] :
Adkins, Ca2+-calmodulin inhibits Ca2+ release mediated by type-1, -2 and -3 inositol trisphosphate receptors. 2000, Pubmed