Apo and InsP₃-bound crystal structures of the ligand-binding domain of an InsP₃ receptor.

Department of Physiology, Howard Hughes Medical Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
Nature Structural & Molecular Biology (Impact Factor: 11.63). 09/2011; 18(10):1172-4. DOI: 10.1038/nsmb.2112
Source: PubMed

ABSTRACT We report the crystal structures of the ligand-binding domain (LBD) of a rat inositol 1,4,5-trisphosphate receptor (InsP(3)R) in its apo and InsP(3)-bound conformations. Comparison of these two conformations reveals that LBD's first β-trefoil fold (β-TF1) and armadillo repeat fold (ARF) move together as a unit relative to its second β-trefoil fold (β-TF2). Whereas apo LBD may spontaneously transition between gating conformations, InsP(3) binding shifts this equilibrium toward the active state.

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