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XB-ART-18503
EMBO J 1996 Mar 01;155:1004-11.
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TWIK-1, a ubiquitous human weakly inward rectifying K+ channel with a novel structure.

Lesage F , Guillemare E , Fink M , Duprat F , Lazdunski M , Romey G , Barhanin J .


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A new human weakly inward rectifying K+ channel, TWIK-1, has been isolated. This channel is 336 amino acids long and has four transmembrane domains. Unlike other mammalian K+ channels, it contains two pore-forming regions called P domains. Genes encoding structural homologues are present in the genome of Caenorhabditis elegans. TWIK-1 currents expressed in Xenopus oocytes are time-independent and present a nearly linear I-V relationship that saturated for depolarizations positive to O mV in the presence of internal Mg2+. This inward rectification is abolished in the absence of internal Mg2+. TWIK-1 has a unitary conductance of 34 pS and a kinetic behaviour that is dependent on the membrane potential. In the presence of internal Mg2+, the mean open times are 0.3 and 1.9 ms at -80 and +80 mV, respectively. The channel activity is up-regulated by activation of protein kinase C and down-regulated by internal acidification. Both types of regulation are indirect. TWIK-1 channel activity is blocked by Ba2+(IC50=100 microM), quinine (IC50=50 microM) and quinidine (IC50=95 microM). This channel is of particular interest because its mRNA is widely distributed in human tissues, and is particularly abundant in brain and heart. TWIK-1 channels are probably involved in the control of background K+ membrane conductances.

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Species referenced: Xenopus laevis
Genes referenced: kcnk1

References [+] :
Aldrich, Potassium channels. New channel subunits are a turn-off. 1994, Pubmed, Xenbase