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)

In this study, the binding of [3H]ryanodine to liver microsomal subfractions was investigated. The specific binding of [3H]ryanodine, as determined both by vacuum filtration and by ultracentrifugation, is to a single class of high-affinity binding sites with a Kd of 10 +/- 2.5 nM and density of 500 +/- 100 and 1200 +/- 200 fmol/mg of protein by the filtration and centrifugation methods respectively. [3H]Ryanodine binding reached equilibrium in about 1 min and 2 min at 36 degrees C and 24 degrees C respectively, and the half-time of dissociation at 37 degrees C was approx. 15 s. The binding of [3H]ryanodine is Ca(2+)-independent: it is slightly stimulated by NaCl, Mg2+, ATP and InsP3 but strongly inhibited by caffeine, diltiazem and sodium dantrolene. Thus the binding of ryanodine to endoplasmic reticulum membranes shares some of the characteristics of its binding to the sarcoplasmic reticulum but also differs from it in several important properties, such as its Ca(2+)-independence, its rapid association and dissociation, and its inhibition by caffeine. The structural similarities between the skeletal muscle and liver binding sites were further explored by employing in vitro DNA amplification techniques, using the known sequence of the skeletal muscle receptor as reference point. The data obtained with this method indicate that the liver does not process mRNA for the skeletal muscle ryanodine receptor.
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PMID:Characterization of high-affinity ryanodine-binding sites of rat liver endoplasmic reticulum. Differences between liver and skeletal muscle. 203 82

The subunit structure of the rabbit skeletal muscle ryanodine receptor-Ca2+ release channel complex was examined following solubilization of heavy sarcoplasmic reticulum membranes in two zwitterionic detergents, 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (Chaps) and Zwittergent 3-14. High and low affinity [3H]ryanodine binding was retained upon solubilization of the complex in Chaps but was lost in Zwittergent 3-14. The purified complex migrated as a single peak with an apparent sedimentation coefficient of approximately 30 and approximately 9 S upon density gradient centrifugation and with isoelectric points of 3.7 and 3.9 upon two-dimensional gel electrophoresis in Chaps and Zwittergent 3-14, respectively. Electron microscopy of negatively stained samples indicated that the distinct four-leaf clover structure of the ryanodine receptor observed in Chaps disappeared following Zwittergent treatment of the 30 S complex and instead showed smaller, round particles. Ferguson plot analysis following sodium dodecyl sulfate-polyacrylamide gel electrophoresis of partial and fully cross-linked and incompletely denatured complexes suggested a stoichiometry of four Mr approximately 400,000 peptides/30 S ryanodine receptor oligomer. [3H]Ryanodine binding to the membrane-bound receptor in 50 microM--1 mM free Ca2+ revealed the presence of both high affinity (KD = 8 nM, Hill coefficient (nH) = 0.9) and low affinity (nH approximately 0.45) sites with a ratio of 1:3. Reduction in free Ca2+ to less than or equal to 0.1 microM or trypsin digestion of the membranes resulted in loss of high affinity but not low affinity ryanodine binding (Hill KD = 5,000 nM, nH = 0.9). Addition of 20 mM caffeine to the nanomolar Ca2+ medium decreased the Hill KD to 1,000 nM without changing the Hill coefficient. Occupation of the low affinity sites altered the rate of [3H]ryanodine dissociation from the high affinity sites. Single channel recordings of the purified ryanodine receptor channel incorporated into planar lipid bilayers also indicated the existence of high and low affinity sites for ryanodine, occupation of which resulted in formation of a subconducting and completely closed state of the channel, respectively. These results are compatible with a subunit structural model of the 30 S ryanodine receptor-Ca2+ release channel complex which comprises a homotetramer of negatively charged and allosterically coupled polypeptides of Mr approximately 400,000.
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PMID:The ryanodine receptor-Ca2+ release channel complex of skeletal muscle sarcoplasmic reticulum. Evidence for a cooperatively coupled, negatively charged homotetramer. 255 Apr 60

Previous studies have demonstrated that skeletal muscle from individuals susceptible to malignant hyperthermia (MH) has a defect associated with the mechanism of calcium release from its intracellular storage sites in the sarcoplasmic reticulum (SR). In this report we demonstrate that the [3H]ryanodine receptor of isolated MH-susceptible (MHS) porcine heavy SR exhibits an altered Ca2+ dependence of [3H]ryanodine binding at the low affinity Ca2+ site as well as a lower Kd for ryanodine (92 versus 265 nM) when compared to normal porcine SR. The Bmax of the normal and MHS [3H] ryanodine receptor (9.3-12.6 pmol/mg) was not significantly different, and analysis of MHS and normal SR proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis did not reveal a significant difference in the intensity of Coomassie Blue staining of the spanning protein/ryanodine receptor region of the gels (Mr greater than 300,000). We also find that MHS porcine muscle intact fiber bundles exhibit a 5-10-fold lower ryanodine threshold for twitch and tetanus inhibition, and contracture onset when compared to normal muscle. Since the SR ryanodine receptor is a calcium release channel as well as a component intimately involved in transverse tubule-SR communication, abnormalities in the skeletal muscle ryanodine receptor may be responsible for the abnormal SR calcium release and contractile properties demonstrated by MHS muscle.
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PMID:Abnormal sarcoplasmic reticulum ryanodine receptor in malignant hyperthermia. 337 71

The effects of ionic composition and strength on rabbit skeletal muscle Ca2+ release channel (ryanodine receptor) activity were investigated in vesicle-45Ca2+ flux, single channel and [3H]ryanodine binding measurements. In <0.01 microM Ca2+ media, the highest 45Ca2+ efflux rate was measured in 0.25 M choline-Cl medium followed by 0.25 M KCl, choline 4-morpholineethanesulfonic acid (Mes), potassium 1,4-piperazinediethanesulfonic acid (Pipes), and K-Mes medium. In all five media, the 45Ca2+ efflux rates were increased when the free [Ca2+] was raised from <0.01 microM to 20 microM and decreased as the free [Ca2+] was further increased to 1 mM. An increase in [KCl] augmented Ca2+-gated single channel activity and [3H]ryanodine binding. In [3H]ryanodine binding measurements, bell-shaped Ca2+ activation/inactivation curves were obtained in media containing different monovalent cations (Li+, Na+, K+, Cs+, and choline+) and anions (Cl-, Mes-, and Pipes-). In choline-Cl medium, substantial levels of [3H]ryanodine binding were observed at [Ca2+] <0.01 microM. Replacement of Cl- by Mes- or Pipes- reduced [3H]ryanodine binding levels at all [Ca2+]. In all media, the Ca2+-dependence of [3H]ryanodine binding could be well described assuming that the skeletal muscle ryanodine receptor possesses cooperatively interacting high-affinity Ca2+ activation and low-affinity Ca2+ inactivation sites. AMP primarily affected [3H]ryanodine binding by decreasing the apparent affinity of the Ca2+ inactivation site(s) for Ca2+, while caffeine increased the apparent affinity of the Ca2+ activation site for Ca2+. Competition studies indicated that ionic composition affected Ca2+-dependent receptor activity by at least three different mechanisms: (i) competitive binding of Mg2+ and monovalent cations to the Ca2+ activation sites, (ii) binding of divalent cations to the Ca2+ inactivation sites, and (iii) binding of anions to specific anion regulatory sites.
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PMID:Regulation of skeletal muscle Ca2+ release channel (ryanodine receptor) by Ca2+ and monovalent cations and anions. 899 38

Interactions between the Ca2+ release channel of skeletal muscle sarcoplasmic reticulum (ryanodine receptor or RyR1) and the loop linking domains II and III (II-III loop) of the skeletal muscle L-type Ca2+ channel (dihydropyridine receptor or DHPR) are critical for excitation-contraction coupling in skeletal muscle. The DHPR II-III loop was fused to glutathione S-transferase- or His-peptide and used as a protein affinity column for 35S-labeled in vitro translated fragments from the N-terminal three-fourths of RyR1. RyR1 residues Leu922-Asp1112 bound specifically to the DHPR II-III loop column, but the corresponding fragment from the cardiac ryanodine receptor (RyR2) did not. The use of chimeras between RyR1 and RyR2 localized the interaction to 37 amino acids, Arg1076-Asp1112, in RyR1. The RyR1 922-1112 fragment did not bind to the cardiac DHPR II-III loop but did bind to the skeletal muscle Na+ channel II-III loop. The skeletal DHPR II-III loop double mutant K677E/K682E lost most of its capacity to interact with RyR1, suggesting that two positively charged residues are important in the interaction between RyR and DHPR.
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PMID:A 37-amino acid sequence in the skeletal muscle ryanodine receptor interacts with the cytoplasmic loop between domains II and III in the skeletal muscle dihydropyridine receptor. 952 69

Dantrolene sodium is a medically important hydantoin derivative that interferes with release of Ca2+ from intracellular stores of skeletal muscle by an unknown mechanism. Identification of the molecular target of dantrolene would greatly aid in understanding both the mechanism of action of the drug and the dynamics of intracellular Ca2+ release in muscle. [3H]Azidodantrolene was designed and synthesized as a photoaffinity analogue in order to identify a putative dantrolene receptor in skeletal muscle. Introduction of 1 mole-atom of tritium into aldehyde 5b was required during radioligand synthesis in order to ensure high enough specific activity for detection of photo-cross-linked proteins by fluorographic methods. This was accomplished by reduction of ester 3 with custom synthesized, 100% tritium-labeled lithium triethylborotritide, followed by oxidation to 5b by manganese(IV) oxide. Compound 6b was demonstrated to be >/=95% tritium-labeled at the imine position by NMR spectroscopy, and the specific radioactivity of [3H]azidodantrolene sodium was empirically determined by HPLC and liquid scintillation counting to be 24.4 Ci/mmol, approximately 85% of theoretical maximum. [3H]Azidodantrolene was found to be pharmacologically active in ligand-receptor binding studies with skeletal muscle sarcoplasmic reticulum membranes. Photo-cross-linking experiments analyzed by SDS-PAGE and tritium fluorography have identified a approximately 160-kDa specifically labeled protein as the putative, intracellular, skeletal muscle dantrolene receptor. This photolabeled protein comigrates with a protein in Western blots immunologically cross-reactive to a polyclonal anti-rabbit skeletal muscle ryanodine receptor antibody. Thus, the putative dantrolene receptor may be related to the skeletal muscle ryanodine receptor.
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PMID:[3H]Azidodantrolene: synthesis and use in identification of a putative skeletal muscle dantrolene binding site in sarcoplasmic reticulum. 1035 95

Selenium compounds, such as sodium selenite and Ebselen were shown to increase high affinity ryanodine binding to the skeletal muscle type ryanodine receptor (RyR1) at nanomolar concentrations, and inhibit the receptor at low micromolar concentrations. This biphasic response was observed in both concentration and time-dependent assays. Extensive washing did not reverse either the stimulation or suppression of receptor binding, but both were prevented or reversed by addition of reduced glutathione, GSH. Selenium compounds were also shown to induce Ca(2+) release from the isolated sarcoplasmic reticulum vesicles. Sodium selenite and Ebselen stimulated the skeletal muscle ryanodine receptor by oxidizing 14 of 47 free thiols per monomer on RyR1 (as detected with the alkylating agent 7-diethylamino-3-(4'-maleimidylphenyl)-4-methylcoumarin) (CPM). Oxidation of the remaining thiols by these selenium compounds resulted in inhibition of the ryanodine receptor.
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PMID:Selenium compounds modulate the calcium release channel/ryanodine receptor of rabbit skeletal muscle by oxidizing functional thiols. 1513 4

The biological activity of nitric oxide (NO) and NO-donors has been extensively investigated yet few studies have examined those of nitroxyl (HNO) species even though both exist in chemical equilibrium but oxidize thiols by different reaction mechanisms: S-nitrosation versus disulfide bond formation. Here, sodium trioxodinitrate (Na2N2O3; Angeli's salt; ANGS) was used as an HNO donor to investigate its effects on skeletal (RyR1) and cardiac (RyR2) ryanodine receptors. At steady-state concentrations of nanomoles/L, HNO induced a rapid Ca2+ release from sarcoplasmic reticulum (SR) vesicles then the reducing agent dithiothreitol (DTT) reversed the oxidation by HNO resulting in Ca2+ re-uptake by SR vesicles. With RyR1 channel proteins reconstituted in planar bilayers, HNO added to the cis-side increased the open probability (Po) from 0.056+/-0.026 to 0.270+/-0.102 (P<0.005, n=4) then DTT (3 mM) reduced Po to 0.096+/-0.040 (P<0.01, n=4). In parallel experiments, the time course of HNO production from ANGS was monitored by EPR and UV spectroscopy and compared with the rate of SR Ca2+ release indicating that picomolar concentrations of HNO triggered SR Ca2+ release. Controls showed that the hydroxyl radical scavenger, phenol did not alter ANGS-induced SR Ca2+ release, indicating that hydroxyl radical production from ANGS did not account for Ca2+ release from the SR. The findings indicate that HNO is a more potent activator of RyR1 than NO and that HNO activation of RyRs may contribute to NO's activation of RyRs and to the therapeutic effects of HNO-releasing prodrugs in heart failure.
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PMID:Nitroxyl triggers Ca2+ release from skeletal and cardiac sarcoplasmic reticulum by oxidizing ryanodine receptors. 1554 67

Selenium (Se) is a trace element that is essential for human health as it takes part in many cellular processes. The cellular response to this compound elicits very diverse processes including DNA damage response and repair. Because an inorganic form of Se, sodium selenite (SeL), has often been a part of numerous studies and because this form of Se is used as a dietary supplement by the public, here, we elucidated mechanisms of SeL-induced toxicity in yeast Saccharomyces cerevisiae using a combination of systematic genetic and transcriptome analysis. First, we screened the yeast haploid deletion mutant library for growth in the presence of this Se compound. We identified 39 highly SeL sensitive mutants. The corresponding deleted genes encoded mostly proteins involved in DNA damage response and repair, vacuole function, glutathione (GSH) metabolism, transcription, and chromatin metabolism. DNA damage response and repair mutants were examined in more detail: a synergistic interaction between postreplication (PRR) and homologous recombination (HRR) repair pathways was revealed. In addition, the effect of combined defects in HRR and GSH metabolism was analyzed, and again, the synergistic interaction was found. Second, microarray analysis was used to reveal expression profile changes after SeL exposure. The gene process categories "amino acid metabolism" and "generation of precursor metabolites and energy" comprised the greatest number of induced and repressed genes, respectively. We propose that SeL-induced toxicity markedly results from DNA injury, thereby highlighting the importance of DNA damage response and repair pathways in protecting cells against toxic effects of this Se compound. In addition, we suggest that SeL toxicity also originates from damage to cellular proteins, including those acting in DNA damage response and repair.
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PMID:Selenium toxicity toward yeast as assessed by microarray analysis and deletion mutant library screen: a role for DNA repair. 2274 91

Duchenne Muscular Dystrophy (DMD) and its murine model, mdx, are characterized by Ca(2+) induced muscle damage and muscle weakness followed by distorted dentofacial morphology. In both, DMD patients and in mdx mice, could be proven so far that only the extraocular muscles (EOM) are not affected by muscular dystrophy. The EOMs are protected against calcium overload by enhanced expression of genes involved in the Ca(2+) homeostasis. We could recently demonstrate that masticatory muscles of mdx mice are differentially affected by muscle dystrophy. The dystrophic masseter and temporalis shows muscle histology comparable to all other skeletal muscles in this animal model, whereas dystrophic tongue muscles seem to develop a milder phenotype. Due to this fact it is to hypothesize that an altered Ca(2+) homeostasis seems to underlie the mdx masticatory muscle pathology. Aim of this study was to examine the mRNA and protein levels of the sarcoplasmic reticulum Ca(2+) ATPases SERCA1 and SERCA2, the plasma membrane Ca(2+) ATPases Atp2b1 and Atp2b4, the sodium/calcium exchanger NCX1, the ryanodine receptor 1, parvalbumin, sarcolipin, phospholamban and the L-type Ca(2+) channel alpha-1 subunit (Cacna1s) in Musculus masseter, temporalis, and tongue of 100 day old control and mdx mice. In mdx masseter muscle significant increased mRNA levels of NCX1 and Cacna1s were found compared to control mice. In contrast, the mRNA amount of RYR1 was significant reduced in mdx temporalis muscle, whereas ATP2b4 was significant increased. In mdx tongue a down-regulation of the ATP2b1, sarcolipin and parvalbumin mRNA expression was found, whereas the phospholamban mRNA level was significantly increased compared to controls. These data were verified by western blot analyses. Our findings revealed that mdx masticatory muscles showed an unequally altered expression of genes involved in the Ca(2+) homeostasis that can support the differences in masticatory muscles response to dystrophin deficiency.
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PMID:Differential expression of genes involved in the calcium homeostasis in masticatory muscles of MDX mice. 2478 40


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