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Small Conductance Ca 2+ ‐Activated K + Channels Formed by the Expression of Rat SK1 and SK2 Genes in HEK 293 Cells
Author(s) -
Benton David C. H.,
Monaghan Alan S.,
Hosseini Ramine,
Bahia Parmvir K.,
Haylett Dennis G.,
Moss Guy W. J.
Publication year - 2003
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1113/jphysiol.2003.054551
Subject(s) - apamin , hek 293 cells , sk channel , microbiology and biotechnology , potassium channel , protein subunit , transfection , biophysics , physics , chemistry , biology , ion channel , gene , biochemistry , receptor
The rat SK1 gene ( rSK1 ) does not form functional Ca 2+ ‐activated potassium channels when expressed alone in mammalian cell lines. Using a selective antibody to the rSK1 subunit and a yellow fluorescent protein (YFP) tag we have discovered that rSK1 expression produces protein that remains largely at intracellular locations. We tested the idea that rSK1 may need an expression partner, rSK2, in order to form functional channels. When rSK1 was co‐expressed with rSK2 in HEK 293 cells it increased the current magnitude by 77 ± 34 % (as compared with cells expressing rSK2 alone). Co‐expression of rSK1 with rSK2 also changed the channel pharmacology. The sensitivity of SK current to block by apamin was reduced ~16‐fold from an IC 50 of 94 p m (for SK2 alone) to 1.4 n m (for SK2 and SK1 together). The sensitivity to block by UCL 1848 (a potent small molecule blocker of SK channels) was similarly reduced, ~26‐fold, from an IC 50 of 110 p m to 2.9 n m . These data clearly demonstrate that rSK1 and rSK2 subunits interact. The most likely explanation for this is that the subunits are able to form heteromeric assemblies.