Identification and cloning of TWIK-originated similarity sequence (TOSS): a novel human 2-pore K+ channel principal subunit.
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.
Pountney
D J
DJ
Department of Pediatric Cardiology, New York University School of Medicine, NY 10016, USA. david.pountney@med.nyu.edu
Gulkarov
I
I
Vega-Saenz de Miera
E
E
Holmes
D
D
Saganich
M
M
Rudy
B
B
Artman
M
M
Coetzee
W A
WA
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
D018076:DNA, Complementary; C109137:KCNK1 protein, human; C486372:Kcnk1 protein, mouse; D015221:Potassium Channels; D024683:Potassium Channels, Tandem Pore Domain; D012333:RNA, Messenger