Single-channel properties and pH sensitivity of two-pore domain K+ channels of the TALK family.
The two-pore K2P channel family comprises TASK, TREK, TWIK, TRESK, TALK, and THIK subfamilies, and TALK-1, TALK-2, and TASK-2 are functional members of the TALK subfamily. Here we report for the first time the single-channel properties of TALK-2 and its pHo sensitivity, and compare them to those of TALK-1 and TASK-2. In transfected COS-7 cells, the three TALK K2P channels could be identified easily by their differences in single-channel conductance and gating kinetics. The single-channel conductances of TALK-1, TALK-2, and TASK-2 in symmetrical 150 mM KCl were 21, 33, and 70 pS (-60 mV), respectively. TALK-2 was sensitive mainly to the alkaline range (pH 7-10), whereas TALK-1 and TASK-2 were sensitive to a wider pHo range (6-10). The effect of pH changes was mainly on the opening frequency. Thus, members of the TALK family expressed in native tissues may be identified based on their single-channel kinetics and pHo sensitivity.
Kang
Dawon
D
Department of Physiology and Biophysics, The Chicago Medical School, 3333 Green Bay Road, North Chicago, IL 60064, USA.
Kim
Donghee
D
D000818:Animals; D015152:Blotting, Northern; D019556:COS Cells; D006863:Hydrogen-Ion Concentration; D015640:Ion Channel Gating / Q000502:physiology; D008564:Membrane Potentials / Q000502:physiology; D008958:Models, Molecular; D018408:Patch-Clamp Techniques / Q000379:methods; D010802:Phylogeny; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D024683:Potassium Channels, Tandem Pore Domain / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011487:Protein Conformation; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D014018:Tissue Distribution; D014162:Transfection
C477398:KCNK16 protein, human; D015221:Potassium Channels; D024683:Potassium Channels, Tandem Pore Domain; D012333:RNA, Messenger