title: Immunological and physical characterization of the brain G protein-gated muscarinic potassium channel.
abstract: The subunit composition of the G protein-gated inwardly rectifying K+ (KG) channel protein extracted from mouse forebrain membranes was examined. A polyclonal antibody (anti-GIRK1C1) was prepared against the carboxyl terminal region of GIRK1, the major subunit of the KG channel. The anti-GIRK1C1 IgG detected a single protein at approximately 65 kDa in SDS-PAGe of brain membranes. This IgG immunoprecipitated a macroprotein complex composed of GIRK1 and several associated proteins whose molecular weights ranging from 50 to 62 kDa on SDS-polyacrylamide gel. Upon size fractionation by both sucrose density gradient centrifugation and gel filtration, the solubilized KG channel proteins migrated into a single peak, which suggests that the component subunits form a single macromolecule. On the basis of the values of size fractionation, the molecular mass of the KG channel macromolecule could be estimated at approximately 231,000. These results suggest that the KG channel is most likely a tetrameric macroprotein composed of GIRK1 and co-immunoprecipitated proteins in the forebrain.
authors.affiliation: Department of Cell Biology and Signaling, Yamagata University School of Medicine, Japan.
authors.forename: A
authors.initials: A
authors.lastname: Inanobe
authors.forename: H
authors.initials: H
authors.lastname: Ito
authors.forename: M
authors.initials: M
authors.lastname: Ito
authors.forename: Y
authors.initials: Y
authors.lastname: Hosoya
authors.forename: Y
authors.initials: Y
authors.lastname: Kurachi
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001923:Brain Chemistry; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D019204:GTP-Binding Proteins / Q000737:chemistry*; D015640:Ion Channel Gating; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000737:chemistry; D015221:Potassium Channels / Q000737:chemistry* / Q000276:immunology; D024661:Potassium Channels, Inwardly Rectifying; D011976:Receptors, Muscarinic / Q000737:chemistry* / Q000276:immunology
chemical_list: D051676:G Protein-Coupled Inwardly-Rectifying Potassium Channels; D009419:Nerve Tissue Proteins; D015221:Potassium Channels; D024661:Potassium Channels, Inwardly Rectifying; D011976:Receptors, Muscarinic; D019204:GTP-Binding Proteins