Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
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.
 ...
PMID:Characterization of high-affinity ryanodine-binding sites of rat liver endoplasmic reticulum. Differences between liver and skeletal muscle. 203 82

The sequence of 4968 (or 4976 with an insertion) amino acids composing the ryanodine receptor from rabbit cardiac sarcoplasmic reticulum has been deduced by cloning and sequencing the cDNA. This protein is homologous in amino acid sequence and shares characteristic structural features with the skeletal muscle ryanodine receptor. Xenopus oocytes injected with mRNA derived from the cardiac ryanodine receptor cDNA exhibit Ca2(+)-dependent Cl- current in response to caffeine, which indicates the formation of functional calcium release channels. RNA blot hybridization analysis with a probe specific for the cardiac ryanodine receptor mRNA shows that the stomach and brain contain a hybridizable RNA species with a size similar to that of the cardiac mRNA. This result, in conjunction with cloning and analysis of partial cDNA sequences, suggests that the brain contains a cardiac type of ryanodine receptor mRNA.
 ...
PMID:Primary structure and functional expression from cDNA of the cardiac ryanodine receptor/calcium release channel. 222 1

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.
 ...
PMID:The ryanodine receptor-Ca2+ release channel complex of skeletal muscle sarcoplasmic reticulum. Evidence for a cooperatively coupled, negatively charged homotetramer. 255 Apr 60

Combined patch-clamp and fura-2 measurements were performed to study the calcium release properties of Chinese hamster ovary (CHO) cells transfected with the rabbit skeletal muscle ryanodine receptor cDNA carried by an expression vector. Both caffeine (1-50 mM) and ryanodine (100 microM) induced release of calcium from intracellular stores of transformed CHO cells but not from control (non-transfected) CHO cells. The calcium responses to caffeine and ryanodine closely resembled those commonly observed in skeletal muscle. Repetitive applications of caffeine produced characteristic all-or-none rises in intracellular calcium. Inositol 1,4,5-trisphosphate (IP3) neither activated the ryanodine receptor channel nor interfered with the caffeine-elicited calcium release. These results indicate that functional calcium release channels are formed by expression of the ryanodine receptor cDNA.
 ...
PMID:Functional expression of the calcium release channel from skeletal muscle ryanodine receptor cDNA. 255 44

We have used [3H]ryanodine binding experiments and single channel recordings to provide convergent descriptions of the effect of imperatoxin A (IpTxa), a approximately 5-kDa peptide from the venom of the scorpion Pandinus imperator (Valdivia, H. H., Kirby, M. S., Lederer, W. J., and Coronado, R. (1992) Proc. Ntl. Acad. Sc. U.S.A. 89, 12185-12189) on Ca2+ release channels/ryanodine receptors (RyR) of sarcoplasmic reticulum (SR). At nanomolar concentrations, IpTxa increased the binding of [3H]ryanodine to skeletal SR and, to a lesser extent, to cerebellum microsomes. The activating effect of IpTxa on skeletal SR was Ca(2+)-dependent, synergized by caffeine, and independent of other modulators of RyRs. However, IpTxa had negligible effects on tissues where the expression of skeletal-type RyR isoforms (RyR1) is small or altogether absent, i.e. cardiac, cerebrum, and liver microsomes. Thus, IpTxa may be used as a ligand capable of discriminating between RyR isoforms with nanomolar affinity. IpTxa increased the open probability (Po) of rabbit skeletal muscle RyRs by increasing the frequency of open events and decreasing the duration of the closed lifetimes. This activating effect was dose-dependent (ED50 = 10 nM), had a fast onset, and was fully reversible. Purified RyR from solubilized skeletal SR displayed high affinity for [3H]ryanodine with a KD of 6.1 nM and Bmax of approximately 30 pmol/mg of protein. IpTxa increased [3H]ryanodine binding noncompetitively by increasing Bmax to approximately 60 pmol/mg of protein. These results suggested the presence of an IpTxa-binding site on the RyR or a closely associated regulatory protein. This site appears to be distinct from the caffeine- and adenine nucleotide-regulatory sites. IpTxa may prove a useful tool to identify regulatory domains critical for channel gating and to dissect the contribution of skeletal-type RyRs to intracellular Ca2+ waveforms generated by stimulation of different RyR isoforms.
 ...
PMID:Peptide probe of ryanodine receptor function. Imperatoxin A, a peptide from the venom of the scorpion Pandinus imperator, selectively activates skeletal-type ryanodine receptor isoforms. 749 90

Contraction of skeletal muscle is triggered by the release of Ca2+ from the sarcoplasmic reticulum (SR) after depolarization of transverse tubules. The ryanodine receptor exists as a 'foot' protein in the junctional gap between the sarcoplasmic reticulum and the transverse tubule in skeletal muscle, and is proposed to function as a calcium-release channel during excitation-contraction (E-C) coupling. Previous complementary DNA-cloning studies have defined three distinct subtypes of the ryanodine receptor in mammalian tissues, namely skeletal muscle, cardiac and brain types. We report here mice with a targeted mutation in the skeletal muscle ryanodine receptor gene. Mice homozygous for the mutation die perinatally with gross abnormalities of the skeletal muscle. The contractile response to electrical stimulation under physiological conditions is totally abolished in the mutant muscle, although ryanodine receptors other than the skeletal-muscle type seem to exist because the response to caffeine is retained. Our results show that the skeletal muscle ryanodine receptor is essential for both muscular maturation and E-C coupling, and also imply that the function of the skeletal muscle ryanodine receptor during E-C coupling cannot be substituted by other subtypes of the receptor.
 ...
PMID:Excitation-contraction uncoupling and muscular degeneration in mice lacking functional skeletal muscle ryanodine-receptor gene. 751 81

Microsomal sarcoplasmic reticulum (SR) fractions from lobster skeletal muscle were found to bind [3H]-ryanodine. [3H]-ryanodine binding was enhanced by AMP, Ca2+ and caffeine, and significantly diminished by ATP, Ba2+ and Sr2+. Furthermore, dantrolene and ruthenium red, two classical inhibitors of Ca2+ release from the SR, blocked [3H]-ryanodine binding. Similarly, tetracaine, known to block the charge movement associated with excitation-contraction coupling in vertebrate muscle, inhibited the binding of the alkaloid. Our lobster SR preparation exhibited a single high-affinity ryanodine binding site (Kd = 6.6 nM, Bmax = 10 pmol/mg protein). Since SDS-PAGE of the SR proteins revealed a major band c. 565 kDa which comigrated with the putative ryanodine receptor from both rat and chicken skeletal muscle, we concluded that lobster skeletal muscle is equipped with the 565 kDa ryanodine receptor. Finally, incorporation of the SR microsomal fraction from lobster into planar bilayer membranes revealed the presence of a ryanodine-sensitive Ca2+ channel activity (160 pS in symmetrical 200 mM CsCl solutions). We concluded that both the crustacean and vertebrate skeletal muscle ryanodine receptor share the relevant properties such as molecular weight and affinity for ryanodine and inositol 1,4,5 triphosphate. However, there are important differences between the two receptors including differential effects of the alkaloid on the Ca2+ release channel and modulation of the receptor by nucleotides.
 ...
PMID:Properties of the ryanodine receptor present in the sarcoplasmic reticulum from lobster skeletal muscle. 751 63

In earlier studies (Chen, S. R. W., Zhang, L., and MacLennan, D. H. (1992) J. Biol. Chem. 267, 23318-23326), an amino acid sequence, designated 13c2, lying between amino acid residues 4478 and 4512 in the skeletal muscle ryanodine receptor was shown, through the use of a polyclonal antibody, to be involved in Ca(2+)-induced Ca2+ release. In the present study, an immobilized synthetic peptide, PEPEPEPEPE, corresponding to part of the predicted high affinity Ca2+ binding site between residues 4489 and 4499, was used to purify specific antibodies from an anti-13c2 rabbit antiserum. The effect of this affinity-purified, anti-peptide (anti-13cp1) antibody on Ca2+ release channel function was then characterized using single channel recordings across planar lipid bilayers. The anti-peptide antibody inhibited Ca(2+)- or caffeine-activated channel activities without closing the channel but did not diminish ATP-activated channel activity. The addition of ATP reversed the inhibition of the Ca(2+)- or caffeine-activated channel by the antibody, and the antibody-bound, ATP-activated channel was further modulated by Mg2+, ryanodine, and ruthenium red. The major epitopes in the anti-13c2 antibody, previously shown to activate the Ca2+ release channel by increasing the Ca2+ sensitivity of the channel, did not lie in the PE repeat. These results suggest that the PE repeat sequence forms a site involved in the Ca2+ activation pathway.
 ...
PMID:Antibodies as probes for Ca2+ activation sites in the Ca2+ release channel (ryanodine receptor) of rabbit skeletal muscle sarcoplasmic reticulum. 768 61

The fluorogenic maleimide 7-diethylamino-3-(4'-maleimidylphenyl)-4-methylcoumarin (CPM) has been shown to selectively form Michael adducts with hyperreactive sulfhydryls on the skeletal sarcoplasmic reticulum (SR) ryanodine receptor (RyR1) and triadin which are essential for normal Ca2+ channel function (Liu, G., Abramson, J.J., Zable, A.C., and Pessah, I.N. (1994) Mol. Pharmacol. 45, 189-200). The present report demonstrates a functionally important interaction between RyR1 and triadin which involves, in part, redox cycling of hyperreactive sulfhydryls in response to channel activation and inactivation. Nanomolar CPM is shown to selectively label RyR1 and triadin only in the presence of Ca2+ channel inhibitors (Mg2+, neomycin, ruthenium red, or anti-triadin antibody). Treatment of SR with channel activators (micromolar Ca2+, nanomolar ryanodine, or millimolar caffeine), 1) slows CPM labeling kinetics > 10-fold, 2) negates CPM labeling of channel-associated sulfhydryls, and 3) stabilizes a high molecular weight complex (HMWC) which appears on nonreducing SDS-polyacrylamide gel electrophoresis gels. The HMWC is positively identified as RyR1 and triadin by Western blot and immunoprecipitation analyses. High-affinity [3H]ryanodine-binding sites are immunoprecipitated by either anti-RyR1 or anti-triadin antibody dose dependently. 1,4-Naphthoquinone (< or = 40 pmol/micrograms protein) selectively oxidizes hyperreactive sulfhydryls on RyR1 and triadin, induces Ca2+ efflux from SR, and stabilizes the HMWC. The HMWC is reduced by beta-mercaptoethanol or dithiothreitol into its component RyR1 and triadin promoters. The results provide direct evidence for the existence of a functionally important complex between RyR1 and triadin whose stability is determined by the redox state of hyperreactive sulfhydryl moieties which are allosterically regulated by physiological and pharmacological channel ligands. The present results suggest a possible molecular mechanism by which localized transient changes in the redox state within the RyR1-triadin complex can signal information across the SR membrane.
 ...
PMID:Molecular interaction between ryanodine receptor and glycoprotein triadin involves redox cycling of functionally important hyperreactive sulfhydryls. 780 31

Single strand conformational polymorphism analysis was used to screen exons 43 and 44 in the skeletal muscle ryanodine receptor gene from 17 positively diagnosed members of families in which chromosome 19-linked malignant hyperthermia (MH) was segregating. A polymorphism in two unrelated individuals was found to result from the substitution of A for G7297, leading to the substitution of Arg for Gly2433. This mutation is adjacent to a mutation (Arg2434 to His) previously linked to MH and central core disease (Y. Zhang et al., Nature Genet. 1993, 5, 46-50). Subsequent screening showed the presence of the mutation in four of 106 MH families tested and its absence from about 1000 other chromosomes. The mutation was present in all six individuals in four families who had had an MH reaction, in two obligate carriers and in 10 individuals diagnosed as MH susceptible by the caffeine/halothane contracture test (CHCT). The mutation was present in an individual with a normal response to the CHCT and was absent in three individuals with a positive CHCT response. These discrepancies would be consistent with inaccuracies in the CHCT and/or with segregation of a second MH allele within two of the four affected families.
 ...
PMID:The substitution of Arg for Gly2433 in the human skeletal muscle ryanodine receptor is associated with malignant hyperthermia. 788 17


1 2 3 4 5 6 7 8 9 10 Next >>