Level of expression controls modes of gating of a K+ channel.
Several distinct subfamilies of K+ channel genes have been discovered by molecular cloning, however, in some cases the structural differences among them do not account for the diversity of K+ current types, ranging from transient A-type to slowly inactivating delayed rectifier-type, as members within each subfamily have been shown to code for K+ channels of different inactivation kinetics and pharmacological properties. We show that a single K+ channel cDNA of the Shaker subfamily (ShH4) can express in Xenopus oocytes not only a transient A-type K+ current but also, upon increased level of expression, slowly inactivating K+ currents with markedly reduced sensitivity to tetraethylammonium. In correlation with the macroscopic currents there are single-channel gating modes ranging from the fast-inactivation mode which underlies the transient A-type current, to slow-inactivation modes characterized by bursts of longer openings, and corresponding to the slowly inactivating macroscopic currents.
Moran
O
O
Department of Physiology and Pharmacology, Sackler School of Medicine, Tel Aviv University, Ramat Aviv, Israel.
Schreibmayer
W
W
Weigl
L
L
Dascal
N
N
Lotan
I
I
D000818:Animals; D004330:Drosophila; D004553:Electric Conductivity; D005786:Gene Expression Regulation; D015640:Ion Channel Gating; D007700:Kinetics; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D012313:RNA / Q000378:metabolism; D014981:Xenopus
D015221:Potassium Channels; D012313:RNA