UNIPROT:P21817 - FACTA Search

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)

We tested the hypothesis that part of the lumenal amino acid segment between the two most C-terminal membrane segments of the skeletal muscle ryanodine receptor (RyR1) is important for channel activity and conductance. Eleven mutants were generated and expressed in HEK293 cells focusing on amino acid residue I4897 homologous to the selectivity filter of K(+) channels and six other residues in the M3-M4 lumenal loop. Mutations of amino acids not absolutely conserved in RyRs and IP(3)Rs (D4903A and D4907A) showed cellular Ca(2+) release in response to caffeine, Ca(2+)-dependent [(3)H]ryanodine binding, and single-channel K(+) and Ca(2+) conductances not significantly different from wild-type RyR1. Mutants with an I4897 to A, L, or V or D4917 to A substitution showed a decreased single-channel conductance, loss of high-affinity [(3)H]ryanodine binding and regulation by Ca(2+), and an altered caffeine-induced Ca(2+) release in intact cells. Mutant channels with amino acid residue substitutions that are identical in the RyR and IP(3)R families (D4899A, D4899R, and R4913E) exhibited a decreased K(+) conductance and showed a loss of high-affinity [(3)H]ryanodine binding and loss of single-channel pharmacology but maintained their response to caffeine in a cellular assay. Two mutations (G4894A and D4899N) were able to maintain pharmacological regulation both in intact cells and in vitro but had lower single-channel K(+) and Ca(2+) conductances than the wild-type channel. The results support the hypothesis that amino acid residues in the lumenal loop region between the two most C-terminal membrane segments constitute a part of the ion-conducting pore of RyR1.
...
PMID:Evidence for a role of the lumenal M3-M4 loop in skeletal muscle Ca(2+) release channel (ryanodine receptor) activity and conductance. 1092 15

A negatively charged region of the N-terminal portion of the skeletal ryanodine receptor (RyR), located between residues 1872-1923, is involved in Ca (2+)-dependent regulation of the Ca(2+)-release channel. This region is divergent between the skeletal (RyR1) and cardiac (RyR2) isoforms of the channel, and is known as D3. Ca(2+) exerts important regulatory functions on the RyR, being involved in both activation and inactivation functions of the channel, i.e. the effects occurring at micromolar and millimolar Ca(2+) concentrations respectively. To characterize the role of D3 in the Ca(2+)-dependent regulation of the Ca(2+)-release channel, we studied the functional consequences of deleting the D3 region from RyR1 (DeltaD3-RyR1) using a heterologous expression system, [(3)H]ryanodine binding assays and single-channel recordings in lipid bilayers. Deletion of the D3 region selectively affected Ca(2+)-dependent regulation of RyR1, but did not alter [(3)H]ryanodine binding or the effect of other modulators on the RyR. Compared with full-length RyR1 (wt-RyR1), the Ca(2+)-dependence curve of DeltaD3-RyR1 is broader, reflecting increased sensitivity to Ca(2+) activation and decreased sensitivity to Ca(2+) inactivation. In addition, DeltaD3-RyR1 was more resistant to inhibition by Mg(2+). Comparison of the effect of caffeine on wt-RyR1 and DeltaD3-RyR1 suggested that D3 is an important region of RyR that participates in Ca(2+)-dependent activation and inactivation of the Ca(2+)-release channel.
...
PMID:Characterization of a calcium-regulation domain of the skeletal-muscle ryanodine receptor. 1099 47

Of the three known ryanodine receptor (RyR) isoforms expressed in muscle, RyR1 and RyR2 have well-defined roles in contraction. However, studies on mammalian RyR3 have been difficult because of low expression levels relative to RyR1 or RyR2. Using the herpes simplex virus 1 (HSV-1) helper-free amplicon system, we expressed either RyR1 or RyR3 in 1B5 RyR-deficient myotubes. Western blot analysis revealed that RyR1- or RyR3-transduced cells expressed the appropriate RyR isoform of the correct molecular mass. Although RyR1 channels exhibited the expected unitary conductance for Cs(+) in bilayer lipid membranes, 74 of 88 RyR3 channels exhibited pronounced subconductance behavior. Western blot analysis with an FKBP12/12.6-selective antibody reveals that differences in gating behavior exhibited by RyR1 and RyR3 may be, in part, the result of lower affinity of RyR3 for FKBP12. In calcium imaging studies, RyR1 restored skeletal-type excitation-contraction coupling, whereas RyR3 did not. Although RyR3-expressing myotubes were more sensitive to caffeine than those expressing RyR1, they were much less sensitive to 4-chloro-m-cresol (CMC). In RyR1-expressing cells, regenerative calcium oscillations were observed in response to caffeine and CMC but were never seen in RyR3-expressing 1B5 cells. In [(3)H]ryanodine binding studies, only RyR1 exhibited sensitivity to CMC, but both RyR isoforms responded to caffeine. These functional differences between RyR1 and RyR3 expressed in a mammalian muscle context may reflect differences in association with accessory proteins, especially FKBP12, as well as structural differences in modulator binding sites.
...
PMID:Divergent functional properties of ryanodine receptor types 1 and 3 expressed in a myogenic cell line. 1105 26

Central core disease (CCD) and nemaline myopathy (NM) are congenital myopathies for which differential diagnosis is often based on the presence either of cores or rods. Missense mutations in the skeletal muscle ryanodine receptor gene (RYR1) have been identified in some families with CCD. Mutations in the alpha-tropomyosin and alpha-actin genes have been associated with most dominant forms of NM. Analysis of the RYR1 cDNA in a French family identified a novel Y4796C mutation that lies in the C-terminal channel-forming domain of the RyR1 protein. This mutation was linked not only to a severe and penetrant form of CCD, but also to the presence of rods in the muscle fibres and to the malignant hyperthermia susceptibility (MHS) phenotype. The Y4796C mutation was introduced into a rabbit RYR1 cDNA and expressed in HEK-293 cells. Expression of the mutant RYR1 cDNA produced channels with increased caffeine sensitivity and a significantly reduced maximal level of Ca(2+) release. Single-cell Ca(2+) analysis showed that the resting cytoplasmic level was increased by 60% in cells expressing the mutant channel. These data support the view that the rate of Ca(2+) leakage is increased in the mutant channel. The resulting chronic elevation in myoplasmic concentration is likely to be responsible for the severe expression of the disease. Haplotyping analysis indicated that the mutation arose as a neomutation in the proband. This first report of a neomutation in the RYR1 gene has strong implications for genetic linkage studies of MHS or CCD, two diseases characterized by a genetic heterogeneity.
...
PMID:An autosomal dominant congenital myopathy with cores and rods is associated with a neomutation in the RYR1 gene encoding the skeletal muscle ryanodine receptor. 1106 19

We investigated the interaction of the 12 kDa FK506-binding protein (FKBP12) with two ryanodine-receptor isoforms (RyR1 and RyR3) and with two myo-inositol 1,4,5-trisphosphate (IP3) receptor isoforms (IP3R1 and IP3R3). Using glutathione S-transferase (GST)-FKBP12 affinity chromatography, we could efficiently extract RyR1 (42+/-7% of the solubilized RyR1) from terminal cisternae of skeletal muscle as well as RyR3 (32+/-4% of the solubilized RyR3) from RyR3-overexpressing HEK-293 cells. These interactions were completely abolished by FK506 (20 microM) but were largely unaffected by RyR-channel modulators. In contrast, neither IP3R1 nor IP3R3 from various sources, including rabbit cerebellum, A7r5 smooth-muscle cells and IP3R-overexpressing Sf9 insect cells from Spodoptera frugiperda, were retained on the GST-FKBP12 matrix. Moreover, immunoprecipitation experiments indicated a high-affinity interaction of FKBP12 with RyR1 but not with IP3R1. In order to determine the FKBP12-binding site, we fragmented both RyR1 and IP33R1 by limited proteolysis. We obtained a 45 kDa fragment of RyR1 that bound to the GST-FKBP12 matrix, indicating that it retained all requirements for FKBP12 binding. This fragment was identified by its interaction with antibody m34C and must therefore contain its epitope (amino acids 2756-2803). However, no fragment of IP3R1 was retained on the column. These molecular data are in agreement with the lack of correlation between FKBP12 and IP3R1 expression in various cell types. The observation that FKBP12 did not affect IP3-induced Ca2+ release but reduced caffeine-induced Ca2+ release also indicated that mature IP3R1 and IP3R3, in contrast to RyR1 and RyR3, did not display a specific, high-affinity interaction with FKBP12.
...
PMID:Characterization and mapping of the 12 kDa FK506-binding protein (FKBP12)-binding site on different isoforms of the ryanodine receptor and of the inositol 1,4,5-trisphosphate receptor. 1117 Nov 21

Mutations in the central domain of the skeletal muscle ryanodine receptor (RyR) cause malignant hyperthermia (MH). A synthetic peptide (DP4) in this domain (Leu-2442-Pro-2477) produces enhanced ryanodine binding and sensitized Ca2+ release in isolated sarcoplasmic reticulum, similar to the properties in MH, possibly because the peptide disrupts the normal interdomain interactions that stabilize the closed state of the RyR (Yamamoto T, El-Hayek R, and Ikemoto N. J Biol Chem 275: 11618-11625, 2000). Here, DP4 was applied to mechanically skinned fibers of rat muscle that had the normal excitation-contraction coupling mechanism still functional to determine whether muscle fiber responsiveness was enhanced. DP4 (100 microM) substantially potentiated the Ca2+ release and force response to caffeine (8 mM) and to low [Mg2+] (0.2 mM) in every fiber examined, with no significant effect on the properties of the contractile apparatus. DP4 also potentiated the response to submaximal depolarization of the transverse tubular system by ionic substitution. Importantly, DP4 did not significantly alter the size of the twitch response elicited by action potential stimulation. These results support the proposal that DP4 causes an MH-like aberration in RyR function and are consistent with the voltage sensor triggering Ca2+ release by destabilizing the closed state of the RyRs.
...
PMID:Effects of a domain peptide of the ryanodine receptor on Ca2+ release in skinned skeletal muscle fibers. 1140 43

A highly conserved amino acid sequence, GVRAGGGIGD(4831), which may form part of the Ca(2+) release channel pore in RyR2, was subjected to Ala scanning or Ala to Val mutagenesis; function was then measured by expression in HEK-293 cells, followed by Ca(2+) photometry, high affinity [(3)H]ryanodine binding, and single-channel recording. All mutants except I4829A and I4829T (corresponding to the I4897T central core disease mutant in RyR1) displayed caffeine-induced Ca(2+) release in HEK-293 cells; only mutants G4826A, I4829V, and G4830A retained high affinity [(3)H]ryanodine binding; and single-channel function was found for all mutants tested, except for G4822A and A4825V. EC(50) values for caffeine-induced Ca(2+) release were increased for G4822A, R4824A, G4826A, G4828A, and D4831A; decreased for V4823A; and unchanged for A4825V, G4827A, I4829V, and G4830A. Ryanodine (10 microm), which did not stimulate Ca(2+) release in wild type (wt), did so in Ala mutants in amino acids 4823-4827. It inhibited the caffeine response in wt and most mutants, but enhanced the amplitude of caffeine-induced Ca(2+) release in mutant G4828A. It also restored caffeine-induced Ca(2+) release in mutants I4829A and I4829T. In single-channel recordings, mutants I4829V and G4830A retained normal conductance, whereas all others had decreased unitary channel conductances ranging from 27 to 540 picosiemens. Single-channel modulation was retained in G4826A, I4829V, and G4830A, but was lost in other mutants. In contrast to wt and G4826A, I4829V, and G4830A, in which divalent metals were preferentially conducted, mutants with loss of modulation had no selectivity of divalent cations over a monovalent cation. Analysis of Gly(4822) to Asp(4831) mutants in RyR2 supports the view that this highly conserved sequence constitutes part of the ion-conducting pore of the Ca(2+) release channel and plays a key role in ryanodine and caffeine binding and activation.
...
PMID:Functional characterization of mutants in the predicted pore region of the rabbit cardiac muscle Ca(2+) release channel (ryanodine receptor isoform 2). 1142 30

The response to caffeine was studied in mouse muscles [diaphragm, soleus, and extensor digitorum longus (EDL)] with different ryanodine receptor isoform (RyR1, RyR3) composition and in single permeabilized muscle fibers dissected from diaphragm of wild-type (WT) and RyR3-deficient (RyR3-/-) mice at 1, 15, 30, and 60 postnatal days (PND). The caffeine response decreased during development, and, in adult mice, was greater in diaphragm, lower in EDL, and intermediate in soleus. This suggests a direct relation between response to caffeine and RyR3 expression. The lack of RyR3 reduced caffeine response in young, but not in adult mice, and did not abolish the age-dependent variation and the intermuscle differences. In diaphragm single fibers, the response to caffeine increased during development and was reduced in fibers lacking RyR3 both at 15 and 60 PND. A population of fibers highly responsive to caffeine was present in adult WT and disappeared in RyR3-/-. The results confirm the contribution of RyR3 to calcium release for contractile response and clarify the contribution of RyR3 to developmental changes and intermuscle differences.
...
PMID:Response to caffeine and ryanodine receptor isoforms in mouse skeletal muscles. 1144 58

The present study performed on chemically skinned skeletal fibres was designed to compare the effects of adenosine on the Ca2+ sensitivity of contractile proteins and on caffeine-induced Ca2+ release in rat slow- (soleus) and fast-twitch (edl) muscles. The tension-pCa relationships were obtained by exposing triton X-100 (1% v/v) skinned fibres sequentially to solutions of decreasing pCa in the presence or in absence of adenosine. Then, changes in caffeine contracture due to adenosine were recorded on saponin (50 microg/ml) skinned fibres. The results show that the sensitivity to Ca2+ of contractile proteins in the presence of different concentrations of caffeine was not significantly modified by adenosine. However, it was proposed that adenosine (0.1-2 mM) reduced the Ca2+ released by caffeine (0.1-10 mM) from the sarcoplasmic reticulum in slow- and fast-twitch fibres and that the soleus was more sensitive to adenosine than edl muscle. The effects of specific A2a and A1 agonists and antagonists were also tested on caffeine contractures. It was found that the A1 antagonist reduced adenosine effect on caffeine response. Then it is proposed that adenosine modulates the sarcoplasmic reticulum Ca2+ release by a direct effect on the RyR1 receptors and/or by an indirect effect mediated by A1 receptors located at the sarcoplasmic level.
...
PMID:Inhibition of caffeine-induced Ca2+ release by adenosine in mammalian skinned slow- and fast-twitch fibres. 1152 Nov 69

Central core disease (CCD) is a human myopathy that involves a dysregulation in muscle Ca(2)+ homeostasis caused by mutations in the gene encoding the skeletal muscle ryanodine receptor (RyR1), the protein that comprises the calcium release channel of the SR. Although genetic studies have clearly demonstrated linkage between mutations in RyR1 and CCD, the impact of these mutations on release channel function and excitation-contraction coupling in skeletal muscle is unknown. Toward this goal, we have engineered the different CCD mutations found in the NH(2)-terminal region of RyR1 into a rabbit RyR1 cDNA (R164C, I404M, Y523S, R2163H, and R2435H) and characterized the functional effects of these mutations after expression in myotubes derived from RyR1-knockout (dyspedic) mice. Resting Ca(2)+ levels were elevated in dyspedic myotubes expressing four of these mutants (Y523S > R2163H > R2435H R164C > I404M RyR1). A similar rank order was also found for the degree of SR Ca(2)+ depletion assessed using maximal concentrations of caffeine (10 mM) or cyclopiazonic acid (CPA, 30 microM). Although all of the CCD mutants fully restored L-current density, voltage-gated SR Ca(2)+ release was smaller and activated at more negative potentials for myotubes expressing the NH(2)-terminal CCD mutations. The shift in the voltage dependence of SR Ca(2)+ release correlated strongly with changes in resting Ca(2)+, SR Ca(2)+ store depletion, and peak voltage-gated release, indicating that increased release channel activity at negative membrane potentials promotes SR Ca(2)+ leak. Coexpression of wild-type and Y523S RyR1 proteins in dyspedic myotubes resulted in release channels that exhibited an intermediate degree of SR Ca(2)+ leak. These results demonstrate that the NH(2)-terminal CCD mutants enhance release channel sensitivity to activation by voltage in a manner that leads to increased SR Ca(2)+ leak, store depletion, and a reduction in voltage-gated Ca(2)+ release. Two fundamentally distinct cellular mechanisms (leaky channels and EC uncoupling) are proposed to explain how altered release channel function caused by different mutations in RyR1 could result in muscle weakness in CCD.
...
PMID:Functional effects of central core disease mutations in the cytoplasmic region of the skeletal muscle ryanodine receptor. 1152 58

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