Small conductance Ca2+-activated K+ channels formed by the expression of rat SK1 and SK2 genes in HEK 293 cells.
The rat SK1 gene (rSK1) does not form functional Ca2+-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 approximately 16-fold from an IC50 of 94 pM (for SK2 alone) to 1.4 nM (for SK2 and SK1 together). The sensitivity to block by UCL 1848 (a potent small molecule blocker of SK channels) was similarly reduced, approximately 26-fold, from an IC50 of 110 pM to 2.9 nM. 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.
Benton
David C H
DC
Department of Pharmacology, University College London, Gower Street, London WC1E 6BT, UK.
Monaghan
Alan S
AS
Hosseini
Ramine
R
Bahia
Parmvir K
PK
Haylett
Dennis G
DG
Moss
Guy W J
GW
D000465:Algorithms; D000818:Animals; D000906:Antibodies / Q000276:immunology; D001030:Apamin / Q000494:pharmacology; D002460:Cell Line; D004594:Electrophysiology; D006801:Humans; D007150:Immunohistochemistry; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000096:biosynthesis / Q000276:immunology / Q000502:physiology*; D024681:Potassium Channels, Calcium-Activated / Q000502:physiology*; D011806:Quinolinium Compounds / Q000494:pharmacology; D051381:Rats; D051640:Small-Conductance Calcium-Activated Potassium Channels; D014162:Transfection; D014981:Xenopus
C414209:8,14-diaza-1,7(1, 4)-diquinolinacyclotetradecaphane; D000906:Antibodies; C496897:KCNN2 protein, human; C496896:Kcnn1 protein, rat; C496899:Kcnn2 protein, rat; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D011806:Quinolinium Compounds; D051640:Small-Conductance Calcium-Activated Potassium Channels; D001030:Apamin