title: Functional characterization of the cardiac ryanodine receptor pore-forming region.
abstract: Ryanodine receptors are homotetrameric intracellular calcium release channels. The efficiency of these channels is underpinned by exceptional rates of cation translocation through the open channel and this is achieved at the expense of the high degree of selectivity characteristic of many other types of channel. Crystallization of prokaryotic potassium channels has provided insights into the structures and mechanisms responsible for ion selection and movement in these channels, however no equivalent structural detail is currently available for ryanodine receptors. Nevertheless both molecular modeling and cryo-electron microscopy have identified the probable pore-forming region (PFR) of the ryanodine receptor (RyR) and suggest that this region contains structural elements equivalent to those of the PFRs of potassium-selective channels. The aim of the current study was to establish if the isolated putative cardiac RyR (RyR2) PFR could form a functional ion channel. We have expressed and purified the RyR2 PFR and shown that function is retained following reconstitution into planar phospholipid bilayers. Our data provide the first direct experimental evidence to support the proposal that the conduction pathway of RyR2 is formed by structural elements equivalent to those of the potassium channel PFR.
authors.affiliation: Institute of Molecular and Experimental Medicine, Cardiff University, Cardiff, United Kingdom. eudenj@cardiff.ac.uk
authors.forename: Joanne
authors.initials: J
authors.lastname: Euden
authors.forename: Sammy A
authors.initials: SA
authors.lastname: Mason
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Williams
mesh_terms: D001483:Base Sequence; D015153:Blotting, Western; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002412:Cations / Q000378:metabolism; D002850:Chromatography, Gel; D020285:Cryoelectron Microscopy; D017931:DNA Primers / Q000235:genetics; D017136:Ion Transport / Q000187:drug effects; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009206:Myocardium / Q000378:metabolism*; D009355:Neomycin / Q000494:pharmacology; D016133:Polymerase Chain Reaction; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA
chemical_list: D002121:Calcium Channel Blockers; D002412:Cations; D017931:DNA Primers; D019837:Ryanodine Receptor Calcium Release Channel; D009355:Neomycin