Molecular identification of the ryanodine receptor Ca2+ sensor.
J Biol Chem, 1998/6/12;273(24):14675-8.
Chen SR[1], Ebisawa K, Li X, Zhang L
Affiliations
PMID: 9614063
Abstract
We have investigated the molecular basis for ryanodine receptor (RyR) activation by Ca2+ by using site-directed mutagenesis together with functional assays consisting of Ca2+ release measurements and single channel recordings in planar lipid bilayers. We report here that a single substitution of alanine for glutamate at position 3885 (located in the putative transmembrane sequence M2 of the type 3 RyR) reduces the Ca2+ sensitivity, as measured by single channel activation, by more than 10,000-fold, without apparent changes in channel conductance and in modulation by other ligands (e.g. ATP and ryanodine). Co-expression of the wild type and mutant RyR proteins results in the synthesis of single channels that have intermediate Ca2+ sensitivities. These results suggest that the glutamates at position 3885 of each monomer may act in a coordinated way to form the Ca2+ sensor in the tetrameric structure corresponding to RyR.
MeSH terms
Amino Acid Sequence; Aniline Compounds; Caffeine; Calcimycin; Calcium; Cell Line; Conserved Sequence; Electrophysiology; Fluorescence; Humans; Lipid Bilayers; Molecular Sequence Data; Mutagenesis, Site-Directed; Mutation; Patch-Clamp Techniques; Ryanodine Receptor Calcium Release Channel; Sequence Homology, Amino Acid; Transfection; Xanthenes
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