title: Three-dimensional location of the imperatoxin A binding site on the ryanodine receptor.
abstract: Cryo-electron microscopy and three-dimensional, single-particle image analysis have been used to reveal the specific binding site of imperatoxin A (IpTx(a)) on the architecture of the calcium release channel/ryanodine receptor from skeletal muscle (RyR1). IpTx(a) is a peptide toxin that binds with high affinity to RyR1 and affects its functioning. The toxin was derivatized with biotin to enhance its detection with streptavidin. IpTx(a) binds to the cytoplasmic moiety of RyR1 between the clamp and handle domains, 11 nm away from the transmembrane pore. The proposed mimicry by IpTx(a) of the dihydropyridine receptor (DHPR) II-III loop, thought to be a main physiological excitation-contraction trigger, suggests that the IpTx(a) binding location is a potential excitation-contraction signal transduction site.
authors.affiliation: Division of Molecular Medicine, Wadsworth Center, Albany, New York 12201-0509, USA. samso@wadsworth.org
authors.forename: M
authors.initials: M
authors.lastname: Samsó
authors.forename: R
authors.initials: R
authors.lastname: Trujillo
authors.forename: G B
authors.initials: GB
authors.lastname: Gurrola
authors.forename: H H
authors.initials: HH
authors.lastname: Valdivia
authors.forename: T
authors.initials: T
authors.lastname: Wagenknecht
mesh_terms: D000494:Allosteric Regulation; D000818:Animals; D001665:Binding Sites; D001710:Biotin; D015220:Calcium Channels / Q000378:metabolism; D020746:Calcium Channels, L-Type; D020285:Cryoelectron Microscopy; D003593:Cytoplasm; D004305:Dose-Response Relationship, Drug; D015640:Ion Channel Gating; D008958:Models, Molecular; D018716:Molecular Mimicry; D009119:Muscle Contraction / Q000502:physiology; D011817:Rabbits; D012433:Ryanodine / Q000378:metabolism; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure*; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D012604:Scorpion Venoms / Q000378:metabolism* / Q000494:pharmacology; D019809:Streptavidin
chemical_list: D015220:Calcium Channels; D020746:Calcium Channels, L-Type; D019837:Ryanodine Receptor Calcium Release Channel; D012604:Scorpion Venoms; C105361:imperatoxin A; D012433:Ryanodine; D001710:Biotin; D019809:Streptavidin