title: Probing luminal negative charge in the type 3 ryanodine receptor.
abstract: In this study, we have investigated block of potassium (K(+)) current by neomycin, a large polycation, from the luminal face of the type 3 ryanodine receptor (RyR3). Previous studies have shown that neomycin is an open channel blocker of RyR2 that interacts with negatively charged residues in the mouth of the conduction pathway to partially occlude it. In the current study, we have used neomycin as a probe to investigate proposed negatively charged regions in the luminal pore mouth of RyR3. Luminal neomycin induces concentration- and voltage-dependent partial block to a subconductance state in RyR3. Blocking parameters calculated in this study show that neomycin has a higher affinity for RyR3 than RyR2, but block may occur at the same site within the pore mouth. The change in affinity may be due to altered negative charge density at the site of interaction.
authors.affiliation: The Laboratory of Functional Immunogenetics, The Babraham Institute, Cambridge CB2 4AT, UK.
authors.forename: Nicholas
authors.initials: N
authors.lastname: Pugh
authors.forename: Fiona C
authors.initials: FC
authors.lastname: Mead-Savery
authors.forename: W John
authors.initials: WJ
authors.lastname: Coadwell
authors.forename: Daniela
authors.initials: D
authors.lastname: Rossi
authors.forename: Vincenzo
authors.initials: V
authors.lastname: Sorrentino
authors.forename: Alan J
authors.initials: AJ
authors.lastname: Williams
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002460:Cell Line; D004553:Electric Conductivity; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects; D008907:Mink; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009355:Neomycin / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism; D017434:Protein Structure, Tertiary; D012433:Ryanodine / Q000494:pharmacology; D019837:Ryanodine Receptor Calcium Release Channel / Q000737:chemistry* / Q000378:metabolism*; D016415:Sequence Alignment; D055672:Static Electricity
chemical_list: D019837:Ryanodine Receptor Calcium Release Channel; D012433:Ryanodine; D009355:Neomycin; D011188:Potassium