title: Identification and cloning of TWIK-originated similarity sequence (TOSS): a novel human 2-pore K+ channel principal subunit.
abstract: We have identified and cloned a new member of the mammalian tandem pore domain K+ channel subunit family, TWIK-originated similarity sequence, from a human testis cDNA library. The 939 bp open reading frame encodes a 313 amino acid polypeptide with a calculated Mr of 33.7 kDa. Despite the same predicted topology, there is a relatively low sequence homology between TWIK-originated similarity sequence and other members of the mammalian tandem pore domain K+ channel subunit family group. TWIK-originated similarity sequence shares a low (< 30%) identity with the other mammalian tandem pore domain K+ channel subunit family group members and the highest identity (34%) with TWIK-1 at the amino acid level. Similar low levels of sequence homology exist between all members of the mammalian tandem pore domain K+ channel subunit family. Potential glycosylation and consensus PKC sites are present. Northern analysis revealed species and tissue-specific expression patterns. Expression of TWIK-originated similarity sequence is restricted to human pancreas, placenta and heart, while in the mouse, TWIK-originated similarity sequence is expressed in the liver. No functional currents were observed in Xenopus laevis oocytes or HEK293T cells, suggesting that TWIK-originated similarity sequence may be targeted to locations other than the plasma membrane or that TWIK-originated similarity sequence may represent a novel regulatory mammalian tandem pore domain K+ channel subunit family subunit.
authors.affiliation: Department of Pediatric Cardiology, New York University School of Medicine, NY 10016, USA. david.pountney@med.nyu.edu
authors.forename: D J
authors.initials: DJ
authors.lastname: Pountney
authors.forename: I
authors.initials: I
authors.lastname: Gulkarov
authors.forename: E
authors.initials: E
authors.lastname: Vega-Saenz de Miera
authors.forename: D
authors.initials: D
authors.lastname: Holmes
authors.forename: M
authors.initials: M
authors.lastname: Saganich
authors.forename: B
authors.initials: B
authors.lastname: Rudy
authors.forename: M
authors.initials: M
authors.lastname: Artman
authors.forename: W A
authors.initials: WA
authors.lastname: Coetzee
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D003001:Cloning, Molecular; D018076:DNA, Complementary; D006801:Humans; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000235:genetics*; D024683:Potassium Channels, Tandem Pore Domain; D012333:RNA, Messenger; D017386:Sequence Homology, Amino Acid; D013737:Testis / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D018076:DNA, Complementary; C109137:KCNK1 protein, human; C486372:Kcnk1 protein, mouse; D015221:Potassium Channels; D024683:Potassium Channels, Tandem Pore Domain; D012333:RNA, Messenger