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 and a longer initial delay.
Does the amount of IsK mRNA injected affect the activation kinetics of IsK in Xenopus oocytes?
The dependence of IsK channel gating on mRNA concentration suggests a novel mechanism for long-term regulation of ion current kinetics via interaction among individual channel proteins.
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.
Cui et al. (1994) studied IsK K+ channel gating. IsK mRNA injection was evaluated on Activation kinetics of IsK. 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 and a longer initial delay.