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)

A rapid assay for high affinity [3H]ryanodine binding to 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (CHAPS)-solubilized recombinant or native Ca2+ release channel proteins (ryanodine receptor, RyR) was devised. The key to preservation of high affinity [3H]ryanodine binding sites in the presence of increasing concentrations of CHAPS was the addition of phosphatidylcholine. This assay was used to characterize the equilibrium and kinetic properties of [3H]ryanodine binding to recombinant skeletal (RyR1) and cardiac (RyR2) Ca2+ release channels and the effects on binding of physiological modulators including ATP, Ca2+, and Mg2+. Both RyR1 and RyR2 had a single high affinity ryanodine binding site and low affinity sites, but [3H]ryanodine binding to recombinant RyR2 was not sensitive to ATP activation or Ca2+ inactivation and was less sensitive to Mg2+ inhibition. The [3H]ryanodine binding assay was used to estimate the expression level of recombinant RyR2 and RyR1, and to show that RyR2 can be expressed at very high levels in HEK-293 cells. Analysis of the properties of recombinant RyR2 and RyR1 by measurement of intracellular Fura-2 fluorescence revealed that the different properties of RyR2 and RyR1 are retained in the recombinant expressed proteins.
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PMID:Characterization of recombinant rabbit cardiac and skeletal muscle Ca2+ release channels (ryanodine receptors) with a novel [3H]ryanodine binding assay. 983 97

The ryanodine receptor/calcium release channel (RyR1) of sarcoplasmic reticulum from rabbit skeletal muscle terminal cisternae (TC) contains four tightly associated FK506-binding proteins (FKBP12). Dissociation and reconstitution studies have shown that RyR1 can be modulated by FKBP12, which helps to maintain the channel in the quiescent state. In this study, we found that the association of FKBP with RyR1 of skeletal muscle is common to each of the five classes of vertebrates. TC from skeletal muscle representing animals from different vertebrates, i.e. mammals (rabbit), birds (chicken), reptiles (turtle), fish (salmon and rainbow trout), and amphibians (frog), were isolated. For each, we find the following: 1) FKBP12 is localized to the TC (there are four FKBP binding sites/ryanodine receptor); 2) soluble FKBP exchanges with the bound form on RyR1 of TC; 3) release of FKBP from terminal cisternae by drug (FK590) treatment leads to a significant reduction in the net calcium loading rate, consistent with channel activation (the calcium loading rate is restored to the control value by reconstitution with FKBP12); and 4) RyR1 of skeletal muscle TC can bind to and exchange with either FKBP12 or FKBP12.6 (FKBP12.6 is the novel FKBP isoform found selectively associated with RyR2 of dog cardiac sarcoplasmic reticulum). We conclude that FKBP is an integral part of the RyR1 of skeletal muscle in each of the classes of vertebrate animals. The studies are consistent with a role for FKBP in skeletal muscle excitation-contraction coupling.
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PMID:FK-binding protein is associated with the ryanodine receptor of skeletal muscle in vertebrate animals. 985 7

The role of intracellular Ca2+ release in the activation of human bladder smooth muscle is controversial. We have measured the expression of mRNA encoding for the ryanodine receptor (RyR) isoforms (RyR1, RyR2 and RyR3) in isolated human detrusor smooth muscle. mRNA for RyR2 was detected in all samples but no mRNA for RyR1 or RyR3 could be found. Human bladder smooth muscle cells in culture are unresponsive to caffeine, suggesting the absence of a functional RyR system. However, mRNA encoding for RyR2 was detected in these cells. Using saponin-permeabilized cells, a Ruthenium Red-sensitive Ca(2+)-dependent 45Ca2+ release could be demonstrated from the sarcoplasmic reticulum (SR). These data confirm the functional presence of Ca(2+)-induced Ca2+ release (CICR) in cells and suggest that the properties of the RyR2 isoform in human detrusor may change when the cells are maintained in culture. The implications of these observations to detrusor smooth muscle function are discussed.
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PMID:Ryanodine receptors in human bladder smooth muscle. 1008 5

FK506-binding protein (FKBP12) has been found to be associated with the skeletal muscle ryanodine receptor (RyR1) (calcium release channel), whereas FKBP12.6, a novel isoform of FKBP, is selectively associated with the cardiac ryanodine receptor (RyR2). For both RyRs, the stoichiometry is 4 FKBP/RyR. Although FKBP12.6 differs from FKBP12 by only 18 of 108 amino acids, FKBP12.6 selectively binds to RyR2 and exchanges with bound FKBP12.6 of RyR2, whereas both FKBP isoforms bind to RyR1 and exchange with bound FKBP12 of RyR1. To assess the amino acid residues of FKBP12.6 that are critical for selective binding to RyR2, the residues of FKBP12.6 that differ with FKBP12 were mutated to the respective residues of FKBP12. RyR2 of cardiac sarcoplasmic reticulum, prelabeled by exchange with [35S]FKBP12.6, was used as assay system for binding/exchange with the mutants. The triple mutant (Q31E/N32D/F59W) of FKBP12.6 was found to lack selective binding to the cardiac RyR2, comparable with that of FKBP12.0. In complementary studies, mutations of FKBP12 to the three critical amino acids of FKBP12.6, conferred selective binding to RyR2. Each of the FKBP12.6 and FKBP12 mutants retained binding to the skeletal muscle RyR1. We conclude that three amino acid residues (Gln31, Asn32, and Phe59) of human FKBP12.6 account for the selective binding to cardiac RyR2.
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PMID:Three amino acid residues determine selective binding of FK506-binding protein 12.6 to the cardiac ryanodine receptor. 1033 16

Ryanodine receptors are a family of intracellular Ca2+ release channel proteins, which exist as tetrameric complexes of large ( approximately 5000 amino acid residue) polypeptide monomers. As well as controlling striated muscle contraction and neurotransmitter release, these channel proteins have been implicated in several pathological states. In order to characterise ryanodine receptors in various tissues, mouse monoclonal antibodies were developed against the type 1 isoform isolated from skeletal muscle. Several of these antibodies recognise ryanodine receptor in skeletal muscle, as well as high molecular weight (k-HMW) protein in kidney microsomes. Like the ryanodine receptor, the k-HMW protein binds 45Ca2+ and sediments as a large complex upon sucrose density-gradient centrifugation. In contrast, the k-HMW protein does not bind ryanodine and is glycosylated. Furthermore, monoclonal and polyclonal antibodies generated against purified k-HMW protein do not recognise skeletal muscle ryanodine receptor. Characterisation of a cDNA clone encoding part of the k-HMW protein revealed that it is likely to be the rabbit homologue of human megalin, an autoimmune antigen in membranous glomerulonephritis. Potential consequences of immunological similarities between ryanodine receptors and megalin are discussed in terms of autoimmune disease.
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PMID:Autoimmune antigen megalin displays similarities with skeletal muscle ryanodine receptor/Ca2+ release channel. 1034 Dec 94

We characterized type 3 ryanodine receptor (RyR3) purified from rabbit diaphragm by immunoaffinity chromatography using a specific antibody. The purified receptor was free from 12-kDa FK506-binding protein, although it retained the ability to bind 12-kDa FK506-binding protein. Negatively stained images of RyR3 show a characteristic rectangular structure that was indistinguishable from RyR1. The location of the D2 segment, which exists uniquely in the RyR1 isoform, was determined as the region around domain 9 close to the corner of the square-shaped assembly, with use of D2-directed antibody as a probe. The RyR3 homotetramer had a single class of high affinity [3H]ryanodine-binding sites with a stoichiometry of 1 mol/mol. In planar lipid bilayers, RyR3 displayed cation channel activity that was modulated by several ligands including Ca2+, Mg2+, caffeine, and ATP, which is consistent with [3H]ryanodine binding activity. RyR3 showed a slightly larger unit conductance and a longer mean open time than RyR1. Whereas RyR1 showed two classes of channel activity with distinct open probabilities (Po), RyR3 displayed a homogeneous and steeply Ca2+-dependent activity with Po approximately 1. RyR3 was more steeply affected in the channel activity by sulfhydryl-oxidizing and -reducing reagents than RyR1, suggesting that the channel activity of RyR3 may be transformed more precipitously by the redox state. This is also a likely explanation for the difference in the Ca2+ dependence of RyR3 between [3H]ryanodine binding and channel activity.
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PMID:Further characterization of the type 3 ryanodine receptor (RyR3) purified from rabbit diaphragm. 1035 90

To study the function and regulation of the cardiac ryanodine receptor (RyR2) Ca(2+) release channel, we expressed the RyR2 proteins in a Chinese hamster ovary (CHO) cell line, and assayed its function by single channel current recording and confocal imaging of intracellular Ca(2+) ([Ca(2+)](i)). The 16-kb cDNA encoding the full-length RyR2 was introduced into CHO cells using lipofectAmine and electroporation methods. Incorporation of microsomal membrane vesicles isolated from these transfected cells into lipid bilayer membrane resulted in single Ca(2+) release channel activities similar to those of the native Ca(2+) release channels from rabbit cardiac muscle SR membranes, both in terms of gating kinetics, conductance, and ryanodine modification. The expressed RyR2 channels were found to exhibit more frequent transitions to subconductance states than the native RyR2 channels and RyR1 expressed in CHO cells. Caffeine, an exogenous activator of RyR, induced release of [Ca(2+)](i) from these cells. Confocal imaging of cells expressing RyR2 did not detect spontaneous or caffeine-induced local Ca(2+) release events (i.e., "Ca(2+) sparks") typically seen in cardiac muscle. Our data show that the RyR2 expressed in CHO cells forms functional Ca(2+) release channels. Furthermore, the lack of localized Ca(2+) release events in these cells suggests that Ca(2+) sparks observed in cardiac muscle may involve cooperative gating of a group of Ca(2+) release channels and/or their interaction with muscle-specific proteins.
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PMID:Expression and functional characterization of the cardiac muscle ryanodine receptor Ca(2+) release channel in Chinese hamster ovary cells. 1042 27

Cryo-electron microscopy and three-dimensional, single-particle image analysis have been used to reveal the specific binding site of imperatoxin A (IpTx(a)) on the architecture of the calcium release channel/ryanodine receptor from skeletal muscle (RyR1). IpTx(a) is a peptide toxin that binds with high affinity to RyR1 and affects its functioning. The toxin was derivatized with biotin to enhance its detection with streptavidin. IpTx(a) binds to the cytoplasmic moiety of RyR1 between the clamp and handle domains, 11 nm away from the transmembrane pore. The proposed mimicry by IpTx(a) of the dihydropyridine receptor (DHPR) II-III loop, thought to be a main physiological excitation-contraction trigger, suggests that the IpTx(a) binding location is a potential excitation-contraction signal transduction site.
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PMID:Three-dimensional location of the imperatoxin A binding site on the ryanodine receptor. 1042

The type 3 ryanodine receptor (RyR3) is a ubiquitous calcium release channel that has recently been found in mammalian skeletal muscles. However, in contrast to the skeletal muscle isoform (RyR1), neither the subcellular distribution nor the physiological role of RyR3 are known. Here, we used isoform-specific antibodies to localize RyR3 in muscles of normal and RyR knockout mice. In normal hind limb and diaphragm muscles of young mice, RyR3 was expressed in all fibers where it was codistributed with RyR1 and with the skeletal muscle dihydropyridine receptor. This distribution pattern indicates that RyR3 is localized in the triadic junctions between the transverse tubules and the sarcoplasmic reticulum. During development, RyR3 expression declined rapidly in some fibers whereas other fibers maintained expression of RyR3 into adulthood. Comparing the distribution of RyR3-containing fibers with that of known fiber types did not show a direct correlation. Targeted deletion of the RyR1 or RyR3 gene resulted in the expected loss of the targeted isoform, but had no adverse effects on the expression and localization of the respective other RyR isoform. The localization of RyR3 in skeletal muscle triads, together with RyR1, is consistent with an accessory function of RyR3 in skeletal muscle excitation-contraction coupling.
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PMID:Type 3 and type 1 ryanodine receptors are localized in triads of the same mammalian skeletal muscle fibers. 1044 70

The ryanodine receptor/Ca(2+) release channels from skeletal (RyR1) and cardiac (RyR2) muscle cells exhibit different inactivation profiles by cytosolic Ca(2+). D3 is one of the divergent regions between RyR1 (amino acids (aa) 1872-1923) and RyR2 (aa 1852-1890) and may contain putative binding site(s) for Ca(2+)-dependent inactivation of RyR. To test this possibility, we have deleted the D3 region from RyR1 (DeltaD3-RyR1), residues 1038-3355 from RyR2 (Delta(1038-3355)-RyR2) and inserted the skeletal D3 into Delta(1038-3355)-RyR2 to generate sD3-RyR2. The channels formed by DeltaD3-RyR1 and Delta(1038-3355)-RyR2 are resistant to inactivation by mM [Ca(2+)], whereas the chimeric sD3-RyR2 channel exhibits significant inactivation at mM [Ca(2+)]. The DeltaD3-RyR1 channel retains its sensitivity to activation by caffeine, but is resistant to inactivation by Mg(2+). The data suggest that the skeletal D3 region is involved in the Ca(2+)-dependent regulation of the RyR1 channel.
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PMID:A negatively charged region of the skeletal muscle ryanodine receptor is involved in Ca(2+)-dependent regulation of the Ca(2+) release channel. 1056 89


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