title: Identification of a dantrolene-binding sequence on the skeletal muscle ryanodine receptor.
abstract: Dantrolene is a drug that suppresses intracellular Ca(2+) release from sarcoplasmic reticulum (SR) in skeletal muscle and is used as a therapeutic agent in individuals susceptible to malignant hyperthermia. Although its precise mechanism of action has not been elucidated, we have identified the N-terminal region (amino acids 1-1400) of the skeletal muscle isoform of the ryanodine receptor (RyR1), the primary Ca(2+) release channel in SR, as a molecular target for dantrolene using the photoaffinity analog [(3)H]azidodantrolene. Here, we demonstrate that heterologously expressed RyR1 retains its capacity to be specifically labeled with [(3)H]azidodantrolene, indicating that muscle specific factors are not required for this ligand-receptor interaction. Synthetic domain peptides of RyR1 previously shown to affect RyR1 function in vitro and in vivo were exploited as potential drug binding site mimics and used in photoaffinity labeling experiments. Only DP1 and DP1-2s, peptides containing the amino acid sequence corresponding to RyR1 residues 590-609, were specifically labeled by [(3)H]azidodantrolene. A monoclonal anti-RyR1 antibody that recognizes RyR1 and its 1400-amino acid N-terminal fragment recognizes DP1 and DP1-2s in both Western blots and immunoprecipitation assays and specifically inhibits [(3)H]azidodantrolene photolabeling of RyR1 and its N-terminal fragment in SR. Our results indicate that synthetic domain peptides can mimic a native, ligand-binding conformation in vitro and that the dantrolene-binding site and the epitope for the monoclonal antibody on RyR1 are equivalent and composed of amino acids 590-609.
authors.affiliation: Department of Anesthesia, University of Medicine and Dentistry of New Jersey-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
authors.forename: Kalanethee
authors.initials: K
authors.lastname: Paul-Pletzer
authors.forename: Takeshi
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Manjunatha B
authors.initials: MB
authors.lastname: Bhat
authors.forename: Jianjie
authors.initials: J
authors.lastname: Ma
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ikemoto
authors.forename: Leslie S
authors.initials: LS
authors.lastname: Jimenez
authors.forename: Hiromi
authors.initials: H
authors.lastname: Morimoto
authors.forename: Philip G
authors.initials: PG
authors.lastname: Williams
authors.forename: Jerome
authors.initials: J
authors.lastname: Parness
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D016466:CHO Cells; D006224:Cricetinae; D003620:Dantrolene / Q000378:metabolism*; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism*; D009465:Neuromuscular Agents / Q000378:metabolism*; D011817:Rabbits; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry / Q000378:metabolism*; D014316:Tritium
chemical_list: D009465:Neuromuscular Agents; D019837:Ryanodine Receptor Calcium Release Channel; D014316:Tritium; D003620:Dantrolene