Biomaterial Database

Interdependence of ryanodine binding, oligomeric receptor interactions, and Ca2+ release regulation in junctional sarcoplasmic reticulum. 1991

S Carroll, and J G Skarmeta, and X Yu, and K D Collins, and G Inesi

Department of Biological Chemistry, School of Medicine, University of Maryland, Baltimore 21201-1596.

We have examined ryanodine binding to its receptor (RR) and compared its effect on Ca2+ release to the Ca2+ release triggered by Ca2+ plus ATP, using vesicular fragments of junctional terminal cisternae (JTC) obtained from skeletal muscle. Ryanodine binding is slow (taking hours or days to complete) and is highly temperature (Q10 = 4) and Ca2+ dependent. At equilibrium, the extent of binding increases as the concentration of ryanodine is raised above 10(-9) M, exhibiting negative cooperativity and reaching the stoichiometry of the 560,000-Da RR chains near 10(-5) M ryanodine. The specificity of the high affinity binding is demonstrated by competitive binding of ryanodine analogs. Kinetic studies using rapid filtration show that, in the absence of ryanodine, rapid (k = 15 s-1) release of Ca2+ follows a triggering exposure of loaded JTC vesicles to perfusion media containing Ca2+ plus ATP. Induction of this release has no lag period and displays minimal temperature dependence. In contrast, prolonged exposure of JTC vesicles to low (10(-7) M) ryanodine concentrations changes the JTC to a state permitting slow (k = 1 s-1) release of Ca2+ even in the absence of the Ca2+ plus ATP trigger. Higher (greater than microM) concentrations of ryanodine do not allow any Ca2+ release and prevent even the release normally triggered by Ca2+ plus ATP. Our data suggest that ryanodine binds to the open state of the tetrameric RR, inducing protein conformational changes and altered oligomeric interactions. Binding of the first molecule of ryanodine to one of the four binding sites on the receptor produces a partially closed and low conductance state of the Ca2+ release channel and reduces the ryanodine binding affinity of the remaining sites. Ryanodine occupancy of all four binding sites on the receptor completes closure of the Ca2+ channel and blocks the triggering action of Ca2+ plus ATP. The tetrameric association of the RR chains is demonstrated by crosslinking with bifunctional reagents, generating crosslinked tetramers that retain ryanodine binding and Ca2+ release functions.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D009124	Muscle Proteins	The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN.	Muscle Protein,Protein, Muscle,Proteins, Muscle
D011487	Protein Conformation	The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).	Conformation, Protein,Conformations, Protein,Protein Conformations
D011817	Rabbits	A burrowing plant-eating mammal with hind limbs that are longer than its fore limbs. It belongs to the family Leporidae of the order Lagomorpha, and in contrast to hares, possesses 22 instead of 24 pairs of chromosomes.	Belgian Hare,New Zealand Rabbit,New Zealand Rabbits,New Zealand White Rabbit,Rabbit,Rabbit, Domestic,Chinchilla Rabbits,NZW Rabbits,New Zealand White Rabbits,Oryctolagus cuniculus,Chinchilla Rabbit,Domestic Rabbit,Domestic Rabbits,Hare, Belgian,NZW Rabbit,Rabbit, Chinchilla,Rabbit, NZW,Rabbit, New Zealand,Rabbits, Chinchilla,Rabbits, Domestic,Rabbits, NZW,Rabbits, New Zealand,Zealand Rabbit, New,Zealand Rabbits, New,cuniculus, Oryctolagus
D011950	Receptors, Cholinergic	Cell surface proteins that bind acetylcholine with high affinity and trigger intracellular changes influencing the behavior of cells. Cholinergic receptors are divided into two major classes, muscarinic and nicotinic, based originally on their affinity for nicotine and muscarine. Each group is further subdivided based on pharmacology, location, mode of action, and/or molecular biology.	ACh Receptor,Acetylcholine Receptor,Acetylcholine Receptors,Cholinergic Receptor,Cholinergic Receptors,Cholinoceptive Sites,Cholinoceptor,Cholinoceptors,Receptors, Acetylcholine,ACh Receptors,Receptors, ACh,Receptor, ACh,Receptor, Acetylcholine,Receptor, Cholinergic,Sites, Cholinoceptive
D002118	Calcium	A basic element found in nearly all tissues. It is a member of the alkaline earth family of metals with the atomic symbol Ca, atomic number 20, and atomic weight 40. Calcium is the most abundant mineral in the body and combines with phosphorus to form calcium phosphate in the bones and teeth. It is essential for the normal functioning of nerves and muscles and plays a role in blood coagulation (as factor IV) and in many enzymatic processes.	Coagulation Factor IV,Factor IV,Blood Coagulation Factor IV,Calcium-40,Calcium 40,Factor IV, Coagulation
D000255	Adenosine Triphosphate	An adenine nucleotide containing three phosphate groups esterified to the sugar moiety. In addition to its crucial roles in metabolism adenosine triphosphate is a neurotransmitter.	ATP,Adenosine Triphosphate, Calcium Salt,Adenosine Triphosphate, Chromium Salt,Adenosine Triphosphate, Magnesium Salt,Adenosine Triphosphate, Manganese Salt,Adenylpyrophosphate,CaATP,CrATP,Manganese Adenosine Triphosphate,MgATP,MnATP,ATP-MgCl2,Adenosine Triphosphate, Chromium Ammonium Salt,Adenosine Triphosphate, Magnesium Chloride,Atriphos,Chromium Adenosine Triphosphate,Cr(H2O)4 ATP,Magnesium Adenosine Triphosphate,Striadyne,ATP MgCl2
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D012433	Ryanodine	A methylpyrrole-carboxylate from RYANIA that disrupts the RYANODINE RECEPTOR CALCIUM RELEASE CHANNEL to modify CALCIUM release from SARCOPLASMIC RETICULUM resulting in alteration of MUSCLE CONTRACTION. It was previously used in INSECTICIDES. It is used experimentally in conjunction with THAPSIGARGIN and other inhibitors of CALCIUM ATPASE uptake of calcium into SARCOPLASMIC RETICULUM.
D012519	Sarcoplasmic Reticulum	A network of tubules and sacs in the cytoplasm of SKELETAL MUSCLE FIBERS that assist with muscle contraction and relaxation by releasing and storing calcium ions.	Reticulum, Sarcoplasmic,Reticulums, Sarcoplasmic,Sarcoplasmic Reticulums