title: Regulation of the voltage-gated K+ channel KCNA10 by KCNA4B, a novel beta-subunit.
abstract: Voltage-gated K+ (Kv) channels are heteromultimeric complexes consisting of pore-forming alpha-subunits and accessory beta-subunits. Several beta-subunits have been identified and shown to interact with specific alpha-subunits to modify their levels of expression or some of their kinetic properties. The aim of the present study was to isolate accessory proteins for KCNA10, a novel Kv channel alpha-subunit functionally related to Kv and cyclic nucleotide-gated cation channels. Because one distinguishing feature of KCNA10 is a putative cyclic nucleotide-binding domain located at the COOH terminus, the entire COOH-terminal region was used to probe a human cardiac cDNA library using the yeast two-hybrid system. Interacting clones were then rescreened in a functional assay by coinjection with KCNA10 in Xenopus oocytes. One of these clones (KCNA4B), when injected alone in oocytes, produced no detectable current. However, when coinjected with KCNA10, it increased KCNA10 current expression by nearly threefold. In addition, the current became more sensitive to activation by cAMP. KCNA4B can be coimmunoprecipitated with the COOH terminus of KCNA10 and full-length KCNA10. It encodes a soluble protein (141 aa) with no amino acid homology to known beta-subunits but with limited structural similarity to the NAD(P)H-dependent oxidoreductase superfamily. KCNA4B is located on chromosome 13 and spans approximately16 kb, and its coding region is made up of five exons. In conclusion, KCNA4B represents the first member of a new class of accessory proteins that modify the properties of Kv channels.
authors.affiliation: Yale University School of Medicine and West Haven Veterans Administration Medical Center, New Haven, Connecticut 06510, USA.
authors.forename: Shulan
authors.initials: S
authors.lastname: Tian
authors.forename: Weimin
authors.initials: W
authors.lastname: Liu
authors.forename: Yanling
authors.initials: Y
authors.lastname: Wu
authors.forename: Hamid
authors.initials: H
authors.lastname: Rafi
authors.forename: Alan S
authors.initials: AS
authors.lastname: Segal
authors.forename: Gary V
authors.initials: GV
authors.lastname: Desir
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015870:Gene Expression; D015640:Ion Channel Gating / Q000502:physiology*; D007700:Kinetics; D008969:Molecular Sequence Data; D009865:Oocytes / Q000502:physiology; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D017434:Protein Structure, Tertiary; D051637:Shaker Superfamily of Potassium Channels; D020798:Two-Hybrid System Techniques; D014982:Xenopus laevis
chemical_list: C460019:KCNA10 protein, human; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D051637:Shaker Superfamily of Potassium Channels