Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UNIPROT:P21817 (RyR1)
 1,154 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

CCS embryonic stem (ES) cells possessing two mutant alleles (ry1r-/ry1r-) for the skeletal muscle ryanodine receptor (RyR) have been produced and injected subcutaneously into severely compromised immunodeficient mice to produce teratocarcinomas in which Ry1R expression is absent. Several primary fibroblast cell lines were isolated and subcloned from one of these tumors that contain the knockout mutation in both alleles and exhibit a doubling time of 18-24 h, are not contact growth inhibited, do not exhibit drastic morphological change upon serum reduction, and possess the normal complement of chromosomes. Four of these fibroblast clones were infected with a retrovirus containing the cDNA encoding myoD and a puromycin selection marker. Several (1-2 microg/ml) puromycin-resistant subclones from each initial cell line were expanded and examined for their ability to express myoD and to form multinucleated myotubes that express desmin and myosin upon removal of mitogens. One of these clones (1B5 cells) was selected on this basis for further study. These cells, upon withdrawal of mitogens for 5-7 d, were shown by Western blot analysis to express key triadic proteins, including skeletal triadin, calsequestrin, FK506-binding protein, 12 kD, sarco(endo)plasmic reticulum calcium-ATPase1, and dihydropyridine receptors. Neither RyR isoform protein, Ry1R (skeletal), Ry2R (cardiac), nor Ry3R (brain), were detected in differentiated 1B5 cells. Measurements of intracellular Ca2+ by ratio fluorescence imaging of fura-2-loaded cells revealed that differentiated 1B5 cells exhibited no responses to K+ (40 mM) depolarization, ryanodine (50-500 microM), or caffeine (20-100 mM). Transient transfection of the 1B5 cells with the full-length rabbit Ry1R cDNA restored the expected responses to K+ depolarization, caffeine, and ryanodine. Depolarization-induced Ca2+ release was independent of extracellular Ca2+, consistent with skeletal-type excitation-contraction coupling. Wild-type Ry1R expressed in 1B5 cells were reconstituted into bilayer lipid membranes and found to be indistinguishable from channels reconstituted from rabbit sarcoplasmic reticulum with respect to unitary conductance, open dwell times, and responses to ryanodine and ruthenium red. The 1B5 cell line provides a powerful and easily managed homologous expression system in which to study how Ry1R structure relates to function.
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PMID:A transgenic myogenic cell line lacking ryanodine receptor protein for homologous expression studies: reconstitution of Ry1R protein and function. 947 36

Ca(2+)-release from the sarcoplasmic or endoplasmic reticulum, the intracellular Ca(2+) store, is mediated by the ryanodine receptor (RyR) and/or the inositol trisphosphate receptor (IP3R). While IP3R is a ligand(IP3)-operated channel, RyR can be gated by a ligand (Ca(2+)) and/or mechanical coupling with the voltage sensor. There are three genetically distinct isoforms among RyR in mammals: RyR1-3. RyR1, the primary isoform in the skeletal muscle, can be gated by direct or indirect coupling with the conformation change of the alpha 1S subunit of dihydropyridine receptor (DHPR) on the T-tubules (transversely invaginated sarcolemma) upon depolarization of skeletal muscles or by the increased cytoplasmic Ca(2+) (Ca(2+)-induced Ca(2+) release, CICR). RyR2, the primary isoform in the cardiac ventricular muscle (and, in a lesser amount, the brain), can be gated by Ca(2+) which flows in through DHPR, especially the alpha1C subunit on depolarization. RyR3 is distributed ubiquitously in various tissues and may be coexpressed with RyR1 and RyR2. RyR3 is considered to be similar to RyR2 in the respect that it can be activated by Ca(2+), in view of the lack of available evidence to show the activation by the alpha1S subunit. Therefore, it is anticipated that RyR3 might take part through CICR in Ca(2+) signaling in smooth muscle and other non-muscle cells. To address the possible involvement of the CICR mechanism in the Ca(2+) signal transduction, it is critical to assess the effect of Mg(2+) on the CICR activity and the cytoplasmic concentration of Mg(2+). In this brief review, our discussion focuses on the effects of Ca(2+) and Mg(2+) on the activity of RyR3.
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PMID:Putative roles of type 3 ryanodine receptor isoforms (RyR3). 1115 Jul 32