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Nature. 2002 Dec 12;420(6916):696-700. Epub 2002 Nov 17.

Structure of the inositol 1,4,5-trisphosphate receptor binding core in complex with its ligand.

Author information

1
Division of Molecular and Structural Biology, Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, 610 University Avenue, Toronto, Ontario, Canada M5G 2M9.

Abstract

In a variety of cells, the Ca2+ signalling process is mediated by the endoplasmic-reticulum-membrane-associated Ca2+ release channel, inositol 1,4,5-trisphosphate (InsP3) receptor (InsP3R). Being ubiquitous and present in organisms ranging from humans to Caenorhabditis elegans, InsP3R has a vital role in the control of cellular and physiological processes as diverse as cell division, cell proliferation, apoptosis, fertilization, development, behaviour, memory and learning. Mouse type I InsP3R (InsP3R1), found in high abundance in cerebellar Purkinje cells, is a polypeptide with three major functionally distinct regions: the amino-terminal InsP3-binding region, the central modulatory region and the carboxy-terminal channel region. Here we present a 2.2-A crystal structure of the InsP3-binding core of mouse InsP3R1 in complex with InsP3. The asymmetric, boomerang-like structure consists of an N-terminal beta-trefoil domain and a C-terminal alpha-helical domain containing an 'armadillo repeat'-like fold. The cleft formed by the two domains exposes a cluster of arginine and lysine residues that coordinate the three phosphoryl groups of InsP3. Putative Ca2+-binding sites are identified in two separate locations within the InsP3-binding core.

PMID:
12442173
DOI:
10.1038/nature01268
[Indexed for MEDLINE]

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