Functional distinction of human EAG1 and EAG2 potassium channels.
Human ether à go-go potassium channel 2 (hEAG2) was cloned and its properties were compared with the previously characterized isoform hEAG1. In the Xenopus oocyte expression system the time course of activation was about four times slower and the voltage required for half-maximal subunit activation was about 10 mV greater for hEAG2 channels. However, its voltage dependence was smaller and, therefore, hEAG2 channels start to open at more negative voltages than hEAG1. Coexpression of both isoforms and kinetic analysis of the resulting currents indicated that they can form heteromeric channel complexes in which the slow activation phenotype of hEAG2 is dominant. Upon expression in mammalian cells, quinidine blocked hEAG1 channels (IC(50) 1.4 microM) more potently than hEAG2 channels (IC(50) 152 microM), thus providing a useful tool for the functional distinction between hEAG1 and hEAG2 potassium channels.
Schönherr
Roland
R
Arbeitsgruppe Molekulare und Zelluläre Biophysik, Klinikum der Friedrich-Schiller-Universität Jena, Drackendorfer Strasse 1, D-07747 Jena, Germany.
Gessner
Guido
G
Löber
Karsten
K
Heinemann
Stefan H
SH
D000818:Animals; D016466:CHO Cells / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D006224:Cricetinae; D051638:Ether-A-Go-Go Potassium Channels; D015870:Gene Expression; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D008845:Microinjections; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D020033:Protein Isoforms / Q000235:genetics / Q000378:metabolism; D021122:Protein Subunits; D011802:Quinidine / Q000494:pharmacology; D014162:Transfection; D014981:Xenopus
D051638:Ether-A-Go-Go Potassium Channels; C496884:KCNH1 protein, human; C485729:KCNH5 protein, human; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D020033:Protein Isoforms; D021122:Protein Subunits; D011802:Quinidine