Small conductance Ca2+-activated K+ channels formed by the expression of rat SK1 and SK2 genes in HEK 293 cells

• Published in: The Journal of physiology Vol. 553; no. 1; pp. 13 - 19
• Main Authors: Benton, David C. H., Monaghan, Alan S., Hosseini, Ramine, Bahia, Parmvir K., Haylett, Dennis G., Moss, Guy W. J.
• Format: Journal Article
• Language: English
• Published: Oxford, UK The Physiological Society 15-11-2003; Blackwell Publishing Ltd; Blackwell Science Inc
• Subjects: Algorithms; Animals; Antibodies - immunology; Apamin - pharmacology; Cell Line; Electrophysiology; Humans; Immunohistochemistry; Oocytes - metabolism; Patch-Clamp Techniques; Potassium Channel Blockers - pharmacology; Potassium Channels - biosynthesis; Potassium Channels - immunology; Potassium Channels - physiology; Potassium Channels, Calcium-Activated - physiology; Quinolinium Compounds - pharmacology; Rapid Report; Rats; Small-Conductance Calcium-Activated Potassium Channels; Transfection; Xenopus
• ISSN: 0022-3751; 1469-7793
• DOI: 10.1113/jphysiol.2003.054551

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.