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)

The skeletal muscle Ca2+ release channel (ryanodine receptor 1, RYR1) plays an important role in the excitation-contraction coupling process. We purified ryanodine receptor type 1 from rabbit white muscle and adsorbed it to mica sheets with the cytoplasmic side facing up. Single receptors of uniformly distributed size and shape of 10-12 nm height and 40-50 nm width, and occasionally some aggregates were seen in contact mode AFM images. These immobilized RYR1 were specifically recognized by rabbit anti-RYR1 (antibody#8) with at least 30% efficiency, as measured by an enzyme immunoassay with goat-anti-rabbit. Single specific antibody-antigen recognition events were detected with AFM tips to which an antibody#8 was tethered. In linear scans, the occurrence of antibody-antigen binding showed significant lateral dependence, which allowed for the localization of binding sites with nm resolution. Variation of the loading rate in force spectroscopy experiments revealed a logarithmic dependence of the unbinding forces, ranging from 42 to 73 pN. From this dependence, a bond width of the binding pocket of L = 0.2 nm and a kinetic off-rate of koff = 12.7s(-1) was determined.
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PMID:Recognition force microscopy/spectroscopy of ion channels: applications to the skeletal muscle Ca2+ release channel (RYR1). 1121 15

FK506 binding protein (FKBP) is a cytosolic receptor for the immunosuppressive drug FK-506. The common isoform, FKBP12, was found to be associated with the calcium release channel (ryanodine receptor 1) of different species of vertebrate skeletal muscle, whereas 12.6, a novel FKBP isoform was found to be associated with canine cardiac ryanodine receptor (ryanodine receptor 2). Until recently, canine cardiac sarcoplasmic reticulum was considered to be the prototype for studying heart RyR2 and its interactions with FKBP. In this study, cardiac microsomes were isolated from diverse vertebrates: human, rabbit, rat, mice, dog, chicken, frog, and fish and were analyzed for their ability to bind or exchange with FKBP isoforms 12 and 12.6. Our studies indicate that RyR2 from seven out of the eight animals contain both FKBP12 and 12.6. Dog is the exception. It can now be concluded that the association of FKBP isoforms with RyR2 is widely conserved in the hearts of different species of vertebrates.
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PMID:FKBP binding characteristics of cardiac microsomes from diverse vertebrates. 1123 59

Central core disease (CCD) is a human congenital myopathy characterized by fetal hypotonia and proximal muscle weakness that is linked to mutations in the gene encoding the type-1 ryanodine receptor (RyR1). CCD is thought to arise from Ca(2+)-induced damage stemming from mutant RyR1 proteins forming "leaky" sarcoplasmic reticulum (SR) Ca(2+) release channels. A novel mutation in the C-terminal region of RyR1 (I4898T) accounts for an unusually severe and highly penetrant form of CCD in humans [Lynch, P. J., Tong, J., Lehane, M., Mallet, A., Giblin, L., Heffron, J. J., Vaughan, P., Zafra, G., MacLennan, D. H. & McCarthy, T. V. (1999) Proc. Natl. Acad. Sci. USA 96, 4164--4169]. We expressed in skeletal myotubes derived from RyR1-knockout (dyspedic) mice the analogous mutation engineered into a rabbit RyR1 cDNA (I4897T). Here we show that homozygous expression of I4897T in dyspedic myotubes results in a complete uncoupling of sarcolemmal excitation from voltage-gated SR Ca(2+) release without significantly altering resting cytosolic Ca(2+) levels, SR Ca(2+) content, or RyR1-mediated enhancement of dihydropyridine receptor (DHPR) channel activity. Coexpression of both I4897T and wild-type RyR1 resulted in a 60% reduction in voltage-gated SR Ca(2+) release, again without altering resting cytosolic Ca(2+) levels, SR Ca(2+) content, or DHPR channel activity. These findings indicate that muscle weakness suffered by individuals possessing the I4898T mutation involves a functional uncoupling of sarcolemmal excitation from SR Ca(2+) release, rather than the expression of overactive or leaky SR Ca(2+) release channels.
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PMID:Excitation--contraction uncoupling by a human central core disease mutation in the ryanodine receptor. 1127 44

The skeletal muscle Ca(2+) release channel/ryanodine receptor (RyR1) is a prototypic redox-responsive ion channel. Nearly half of the 101 cysteines per RyR1 subunit are kept in a reduced (free thiol) state under conditions comparable with resting muscle. Here we assessed the effects of physiological determinants of cellular redox state (oxygen tension, reduced (GSH) or oxidized (GSSG) glutathione, and NO/O(2) (released by 3-morpholinosydnonimine)) on RyR1 redox state and activity. Oxidation of approximately 10 RyR1 thiols (from approximately 48 to approximately 38 thiols/RyR1 subunit) had little effect on channel activity. Channel activity increased reversibly as the number of thiols was further reduced to approximately 23/subunit, whereas more extensive oxidation (to approximately 13 thiols/subunit) inactivated the channel irreversibly. Neither S-nitrosylation nor tyrosine nitration contributed to these effects. The results identify at least three functional classes of RyR1 thiols and suggest that 1) the channel may be protected from oxidation by a large reservoir of functionally inert thiols, 2) the channel may be designed to respond to moderate oxidative stress by a change in activation setpoint, and 3) the channel is susceptible to oxidative injury under more extensive conditions.
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PMID:Classes of thiols that influence the activity of the skeletal muscle calcium release channel. 1127 99

The ryanodine receptor (RyR1)/calcium release channel on the sarcoplasmic reticulum of skeletal muscle is comprised of four 565,000-dalton RyR1s, each of which binds one FK506 binding protein (FKBP12). RyR1 is required for excitation-contraction coupling in skeletal muscle. FKBP12, a cis-trans peptidyl-prolyl isomerase, is required for the normal gating of the RyR1 channel. In the absence of FKBP12, RyR1 channels exhibit increased gating frequency, suggesting that FKBP12 "stabilizes" the channel in the open and closed states. We now show that substitution of a Gly, Glu, or Ile for Val2461 in RyR1 prevents FKBP12 binding to RyR1, resulting in channels with increased gating frequency. In the case of the V2461I mutant RyR1, normal channel function can be restored by adding FKBP12.6, an isoform of FKBP12. These data identify Val2461 as a critical residue required for FKBP12 binding to RyR1 and demonstrate the functional role for FKBP12 in the RyR1 channel complex.
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PMID:FKBP12 binding modulates ryanodine receptor channel gating. 1127 44

Fusion proteins and full-length mutants were generated to identify the Ca(2+)-free (apoCaM) and Ca(2+)-bound (CaCaM) calmodulin binding sites of the skeletal muscle Ca(2+) release channel/ryanodine receptor (RyR1). [(35)S]Calmodulin (CaM) overlays of fusion proteins revealed one potential Ca(2+)-dependent (aa 3553-3662) and one Ca(2+)-independent (aa 4302-4430) CaM binding domain. W3620A or L3624D substitutions almost abolished completely, whereas V3619A or L3624A substitutions reduced [(35)S]CaM binding to fusion protein (aa 3553-3662). Three full-length RyR1 single-site mutants (V3619A,W3620A,L3624D) and one deletion mutant (Delta4274-4535) were generated and expressed in human embryonic kidney 293 cells. L3624D exhibited greatly reduced [(35)S]CaM binding affinity as indicated by a lack of noticeable binding of apoCaM and CaCaM (nanomolar) and the requirement of CaCaM (micromolar) for the inhibition of RyR1 activity. W3620A bound CaM (nanomolar) only in the absence of Ca(2+) and did not show inhibition of RyR1 activity by 3 microm CaCaM. V3619A and the deletion mutant bound apoCaM and CaCaM at levels compared with wild type. V3619A activity was inhibited by CaM with IC(50) approximately 200 nm, as compared with IC(50) approximately 50 nm for wild type and the deletion mutant. [(35)S]CaM binding experiments with sarcoplasmic reticulum vesicles suggested that apoCaM and CaCaM bind to the same region of the native RyR1 channel complex. These results indicate that the intact RyR1 has a single CaM binding domain that is shared by apoCaM and CaCaM.
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PMID:Identification of apocalmodulin and Ca2+-calmodulin regulatory domain in skeletal muscle Ca2+ release channel, ryanodine receptor. 1130 90

The II-III loop of the skeletal muscle dihydropyridine receptor (DHPR) alpha(1S) subunit is responsible for bidirectional-signaling interactions with the ryanodine receptor (RyR1): transmitting an orthograde, excitation-contraction (EC) coupling signal to RyR1 and receiving a retrograde, current-enhancing signal from RyR1. Previously, several reports argued for the importance of two distinct regions of the skeletal II-III loop (residues R681-L690 and residues L720-Q765, respectively), claiming for each a key function in DHPR-RyR1 communication. To address whether residues 720-765 of the II-III loop are sufficient to enable skeletal-type (Ca(2+) entry-independent) EC coupling and retrograde interaction with RyR1, we constructed a green fluorescent protein (GFP)-tagged chimera (GFP-SkLM) having rabbit skeletal (Sk) DHPR sequence except for a II-III loop (L) from the DHPR of the house fly, Musca domestica (M). The Musca II-III loop (75% dissimilarity to alpha(1S)) has no similarity to alpha(1S) in the regions R681-L690 and L720-Q765. GFP-SkLM expressed in dysgenic myotubes (which lack endogenous alpha(1S) subunits) was unable to restore EC coupling and displayed strongly reduced Ca(2+) current densities despite normal surface expression levels and correct triad targeting (colocalization with RyR1). Introducing rabbit alpha(1S) residues L720-L764 into the Musca II-III loop of GFP-SkLM (substitution for Musca DHPR residues E724-T755) completely restored bidirectional coupling, indicating its dependence on alpha(1S) loop residues 720-764 but its independence from other regions of the loop. Thus, 45 alpha(1S)-residues embedded in a very dissimilar background are sufficient to restore bidirectional coupling, indicating that these residues may be a site of a protein-protein interaction required for bidirectional coupling.
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PMID:Excitation-contraction coupling is unaffected by drastic alteration of the sequence surrounding residues L720-L764 of the alpha 1S II-III loop. 1132 Feb 25

mRNA and protein analyses have previously shown that the diaphragm expresses two ryanodine receptor isoforms: RyR1 and RyR3. RyR1 is the main Ca2+-releasing pathway in this muscle type. We now report the conducting, gating, and immunological properties of the native and purified forms of the less abundant RyR3 channel. The conductance of this native Ca2+-release channel was 330 pS in 50 mM/250 mM trans/cis CsCH3SO3. It was activated by Ca2+ concentrations of 1-1000 microM, and did not inactivate at mM concentrations of Ca2+. Both isoforms were purified by either a sucrose density gradient or immunoprecipitation as > 450 kDa proteins on SDS-PAGE. Western blot analysis confirmed the presence of RyR1 and RyR3, which displayed conductances of 740 +/- 30 and 800 +/- 25 pS, respectively, in 250 mM KCl. We thus provide evidence that one form of the diaphragm SR Ca2+-release channels may be classified as RyR3, with gating properties different from those of the well-characterized RyR1 and RyR2 isoforms.
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PMID:Functional properties of the native type 3 ryanodine receptor Ca2+-release channel from canine diaphragm. 1133 8

In skeletal muscle, an anterograde signal from the dihydropyridine receptor (DHPR) to the ryanodine receptor (RyR1) is required for excitation-contraction (EC) coupling and a retrograde signal from RyR1 to the DHPR regulates the magnitude of the calcium current carried by the DHPR. As a tool for studying biosynthesis and targeting, we constructed a cDNA encoding green fluorescent protein (GFP) fused to the amino terminal of RyR1 and expressed it in dyspedic myotubes. The GFP-RyR1 was present in a restricted domain near the nucleus injected with cDNA and was fully functional, which places constraints on the location of the amino terminal in the folded structure of RyR1.
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PMID:Structure and targeting of RyR1: implications from fusion of green fluorescent protein at the amino-terminal. 1136 Nov 29

Although dissociation of the 12 kDa FK506 binding protein (FKBP12)-type 1 ryanodine receptor (RyR1) complex by macrolide immunosuppressants is well documented, effects of many solutes and drugs have not been quantitated. In the current study, the influence of these on binding between solubilised RyR1 and an FKBP12-glutathione-S-transferase fusion protein was analysed using a novel assay. Association between these two proteins is stable, and is not greatly altered by changes in temperature, pH, cations, and endogenous solutes over physiological ranges. Ascomycin, an FK506 analogue, was identified for the first time as a drug which can disrupt the FKBP12-RyR1 complex.
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PMID:Analysis of type 1 ryanodine receptor-12 kDa FK506-binding protein interaction. 1143 71


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