|Name:||potassium channel, subfamily K, member 7|
|PubMed (10206991):|| Salinas M, Reyes R, Lesage F, Fosset M, Heurteaux C, Romey G, Lazdunski M. Cloning of a new mouse two-P domain channel subunit and a human homologue witha unique pore structure.J Biol Chem. 1999 Apr 23;274(17):11751-60. PMID: 10206991 [PubMed - indexed for MEDLINE]|
Mouse KCNK6 is a new subunit belonging to the TWIK channel family. This 335-amino acid polypeptide has four transmembrane segments, two pore-forming domains, and a Ca2+-binding EF-hand motif. Expression of KCNK6 transcripts is principally observed in eyes, lung, stomach and embryo. In the eyes, immunohistochemistry reveals protein expression only in some of the retina neurons. Although KCNK6 is able to dimerize as other functional two-P domain K+ channels when it is expressed in COS-7 cells, it remains in the endoplasmic reticulum and is unable to generate ionic channel activity. Deletions, mutations, and chimera constructions suggest that KCNK6 is not an intracellular channel but rather a subunit that needs to associate with a partner, which remains to be discovered, in order to reach the plasma membrane. A closely related human KCNK7-A subunit has been cloned. KCNK7 displays an intriguing GLE sequence in its filter region instead of the G(Y/F/L)G sequence, which is considered to be the K+ channel signature. This subunit is alternatively spliced and gives rise to the shorter forms KCNK7-B and -C. None of the KCNK7 structures can generate channel activity by itself. The KCNK7 gene is situated on chromosome 11, in the q13 region, where several candidate diseases have been identified.
|PubMed (11256078):|| Goldstein SA, Bockenhauer D, O'Kelly I, Zilberberg N. Potassium leak channels and the KCNK family of two-P-domain subunits.Nat Rev Neurosci. 2001 Mar;2(3):175-84. Review. PMID: 11256078 [PubMed - indexed for MEDLINE]|
With a bang, a new family of potassium channels has exploded into view. Although KCNK channels were discovered only five years ago, they already outnumber other channel types. KCNK channels are easy to identify because of their unique structure--they possess two preforming domains in each subunit. The new channels function in a most remarkable fashion: they are highly regulated, potassium-selective leak channels. Although leak currents are fundamental to the function of nerves and muscles, the molecular basis for this type of conductance had been a mystery. Here we review the discovery of KCNK channels, what has been learned about them and what lies ahead. Even though two-P-domain channels are widespread and essential, they were hidden from sight in plain view--our most basic questions remain to be answered.