Functional characterization of RK5, a voltage-gated K+ channel cloned from the rat cardiovascular system

FEBS Lett. 1991 Dec 16;295(1-3):211-3. doi: 10.1016/0014-5793(91)81420-d.


A voltage-sensitive K+ channel previously cloned from rat heart designated RK5 (rat Kv4.2) (Roberds and Tamkun, 1991, Proc. Natl. Acad. Sci. USA 88, 1798-1802) was functionally characterized in the Xenopus oocyte expression system. RK5 is a homolog of the Drosophila Shal K+ channel, activates with a rise time of 2.8 ms, has a midpoint for activation of -1 mV and rapidly inactivates with time constants of 15 and 60 ms. RK5 is sensitive to 4-AP, IC50 = 5 mM, and is insensitive to TEA and dendrotoxins. The voltage dependence and kinetics of the RK5 induced currents suggest this channel contributes to the Ito current in heart.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • DNA / genetics
  • Electrophysiology / methods
  • Evoked Potentials
  • Female
  • Heart / physiology*
  • Oocytes / physiology*
  • Polymerase Chain Reaction / methods
  • Potassium Channels / genetics
  • Potassium Channels / physiology*
  • RNA / genetics
  • Xenopus


  • Potassium Channels
  • RNA
  • DNA