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)

We have tested the periodate-oxidized ATP analogue 2',3'-dialdehyde adenosine triphosphate (oATP) as a ligand for the skeletal muscle ryanodine receptor/Ca(2+)-release channel. Ca2+ efflux from passively loaded heavy sarcoplasmic reticulum vesicles of skeletal muscle is biphasic. oATP stimulates the initial phase of Ca2+ release in a concentration-dependent manner (EC50 160 microM), and the efflux proceeds with a half-time in the range 100-200 ms. This oATP-modulated initial rapid Ca2+ release was specifically inhibited by millimolar concentrations of Mg2+ and micromolar concentrations of Ruthenium Red, indicating that the effect of oATP was mediated via the ryanodine receptor. The purified Ca(2+)-release channel was incorporated into planar lipid bilayers, and single-channel recordings were carried out to verify a direct interaction of oATP with the ryanodine receptor. Addition of oATP to the cytoplasmic side activated the channel with an EC50 of 76 microM, which is roughly 30-fold higher than the apparent affinity of ATP. The oATP-induced increase in the open probability of the ryanodine receptor displays a steep concentration-response curve with a Hill coefficient of approximately 2, which suggests a co-operativity of the ATP binding sites in the tetrameric protein. oATP binds to the ryanodine receptor in a quasi-irreversible manner via Schiff base formation between the aldehyde groups of oATP and amino groups in the nucleotide binding pocket. This allows for the covalent specific incorporation of [alpha-32P]oATP by borhydride reduction. A typical adenine nucleotide binding site cannot be identified in the primary sequence of the ryanodine receptor. Our results demonstrate that oATP can be used to probe the structure and function of the nucleotide binding pocket of the ryanodine receptor and presumably of other ATP-regulated ion channels.
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PMID:Activation and labelling of the purified skeletal muscle ryanodine receptor by an oxidized ATP analogue. 775 53

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

We studied whether acetaldehyde, which is produced by alcohol consumption, impacts ryanodine receptor (RyR) activity and muscle force. Exposure to approximately 50-200 microM acetaldehyde enhanced channel activity of frog RyR and rabbit RyR1 incorporated into lipid bilayers. An increase in acetaldehyde to 1 mM modified channel activity in a time-dependent manner, with a brief activation and then inhibition. Application of 200 microM acetaldehyde to frog fibers increased twitch tension. The maximum rate of rise of tetanus tension was accelerated to 1.5 and 1.74 times the control rate on exposure of fibers to 50 and 200 microM acetaldehyde, respectively. Fluorescence monitoring with fluo 3 demonstrated that 200-400 microM acetaldehyde induced Ca(2+) release from the sarcoplasmic reticulum (SR) in frog muscles. Acetaldehyde at 1 mM inhibited twitch tension by approximately 12%, with an increased relaxation time after a small, transient twitch potentiation. These results suggest that moderate concentrations of acetaldehyde can elicit Ca(2+) release from the SR by increasing the open probability of the RyR channel, resulting in increased tension. However, the effects of acetaldehyde at clinical doses (1-30 microM) are unlikely to mediate alcohol-induced acute muscle dysfunction.
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PMID:Acetaldehyde alters Ca2+-release channel gating and muscle contraction in a dose-dependent manner. 1507 18