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Cellular localization and function of K2P1.1 channel in transfected mammalian cells
Author(s) -
Kim Donghee,
Kang Dawon
Publication year - 2007
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.21.5.a539-a
Subject(s) - transfection , endoplasmic reticulum , microbiology and biotechnology , golgi apparatus , subcellular localization , intracellular , green fluorescent protein , endosome , hek 293 cells , biology , chemistry , cell culture , gene , cytoplasm , biochemistry , genetics
K2P1.1 is the first two‐pore domain K+ channel identified in the mammalian tissue. K2P1.1 mRNA is expressed in the brain and in peripheral tissues including heart and kidney. 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. The role of K2P1.1 as a plasma K+ channel, however, remains unclear. K2P1.1 has been reported to form a silent plasma membrane K+ channel that becomes active when desumoylated. To further study the expression and function of K2P1.1, K2P1.1 was tagged with GFP and transfected into Cos‐7 cells. GFP‐K2P1.1 signal was present in intracellular organelles in most cells with low plasma localization. When a K2P1.1 mutant (GFP‐K274E) that does not undergo sumoylation was expressed, its localization was mainly in the endoplasmic reticulum and Golgi. In Cos‐7 cells, the whole‐cell currents following expression of K2P1.1 or K2P1.1(K274E) were small and not different from those of control cells (GFP only). The 36‐pS K+ channel recorded in Cos‐7 cells was an endogenously expressed channel that was unrelated to K2P1.1. Similarly, K2P1.1 or K2P1.1(K274E) showed no measurable currents in HEK273 and HeLa cells. These findings indicate that in mammalian cell lines, K2P1.1 and K2P1.1(K274E) proteins are mainly localized at the intracellular compartment, and do not appear to form functional K+ channels at the plasma membrane. Localization of K2P1.1 in atrial cells will be studied in the future.