Gating of IsK expressed in Xenopus oocytes depends on the amount of mRNA injected.
IsK is a K+ channel of the delayed rectifier type widely distributed throughout both excitable and nonexcitable cells. Its structure is different from other cloned K+ channels and molecular details of its gating remain obscure. Here we show that the activation kinetics of IsK expressed in Xenopus oocytes depend upon the amount of its mRNA injected, with larger amounts resulting in slower activation kinetics with a longer initial delay during activation. Similar changes in activation kinetics occur with time after a single injection of IsK mRNA. We present two kinetic schemes which illustrate how our experimental results could arise. Both imply an interaction among individual channel proteins during IsK activation. The dependence of channel gating on mRNA concentration provides a novel mechanism for long term regulation of ion current kinetics.
Department of Physiology and Biophysics, State University of New York at Stony Brook 11794-8661.
J
J
Cui
R P
RP
Kline
P
P
Pennefather
I S
IS
Cohen
D000818:Animals; D003201:Computers; D005260:Female; D066298:In Vitro Techniques; D015640:Ion Channel Gating; D008564:Membrane Potentials; D008839:Microelectrodes; D009865:Oocytes / Q000378:metabolism*; D015221:Potassium Channels / Q000235:genetics / Q000378:metabolism*; D024642:Potassium Channels, Voltage-Gated; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
D015221:Potassium Channels; D024642:Potassium Channels, Voltage-Gated; D012333:RNA, Messenger; C059983:potassium channel protein I(sk)