Heteropolymeric potassium channels expressed in Xenopus oocytes from cloned subunits.
Voltage-dependent potassium currents were measured in Xenopus oocytes previously injected with RNAs generated in vitro from each of three cloned cDNAs (RBK1, RBK2, and RGK5). The currents differed in their sensitivities to blockade by tetraethylammonium (TEA; respective KDs 0.3, greater than 100, and 10 mM) and in their inactivation during a depolarizing pulse. Injections of RNA combinations (RBK1/RBK2 and RBK1/RGK5) caused currents that had TEA sensitivities different from those expected from the sum, in any proportion, of the two native channels. It is concluded that novel potassium channels are formed by the oocytes injected with two RNAs, presumably by heteropolymerization of subunits; such heteropolymerization would contribute functional diversity to voltage-dependent potassium channels in addition to that provided by a large gene family.
Christie
M J
MJ
Oregon Health Sciences University, Portland 97201.
North
R A
RA
Osborne
P B
PB
Douglass
J
J
Adelman
J P
JP
D000818:Animals; D001921:Brain / Q000378:metabolism; D003001:Cloning, Molecular; D004247:DNA / Q000235:genetics; D005260:Female; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D009865:Oocytes / Q000187:drug effects / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D019789:Tetraethylammonium; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014982:Xenopus laevis
D008565:Membrane Proteins; D015221:Potassium Channels; D013757:Tetraethylammonium Compounds; D019789:Tetraethylammonium; D004247:DNA