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The two‐pore domain K+ channel K2P1.1 (TWIK‐1) is non‐functional in the heart
Author(s) -
Kim Donghee,
Kang Dawon
Publication year - 2008
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.22.1_supplement.971.6
Subject(s) - sumo protein , transfection , mutant , myocyte , chemistry , microbiology and biotechnology , biophysics , biology , biochemistry , gene , ubiquitin
K2P1.1 mRNA is expressed in many regions including human and rat heart. Recent microarray studies suggest that K2P1.1 may be involved in atrial fibrillation, and knockout mice shows deficiency in phosphate/water transport in the kidney. These studies suggest that K2P1.1 would produce a functional K+ current. In the original study, K2P1.1 expressed a functional current, but a later study showed that K2P1.1 was silent because it was normally sumoylated. Thus, desumoylation or K274E mutation to prevent sumoylation was found to open K2P1.1 in oocytes and Cos‐7 cells. A more recent study found that K2P1.1 does not undergo the sumoylation process and that K274E mutation simply increases the current due to a charge effect. In our study, transfection of Cos‐7 cells with K2P1.1 or K274E mutant failed to produce K+ currents. In Cos‐7 cells or in rat cardiac myocytes that express K2P1.1 mRNA, desumoylation also did not activate any K+ currents. Causing oxidative stress using buthionine sulfoxime or hydrogen peroxide (that may alter sumoylation) also failed to cause activation of any new K+ channels in ventricular myocytes. These results support the view that K2P1.1 does not form a functional channel under different physiological conditions. The role of K2P1.1 in cardiac and renal function remains to be determined.