Expression of an inwardly rectifying K+ channel from rat basophilic leukemia cell mRNA in Xenopus oocytes.
Rat basophilic leukemia cells (RBL-2H3) have previously been shown to contain a single type of voltage-activated channel, namely an inwardly rectifying K+ channel, under normal recording conditions. Thus, RBL-2H3 cells seemed like a logical source of mRNA for the expression cloning of inwardly rectifying K+ channels. Injection of mRNA isolated from RBL-2H3 cells into Xenopus oocytes resulted in the expression of an inward current which (1) activated at potentials negative to the K+ equilibrium potential (Ek), (2) decreased in slope conductance near Ek, (3) was dependent on [K+]o and (4) was blocked by external Ba2+ and Cs+. These properties were similar to those of the inwardly rectifying K+ current recorded from RBL-2H3 cells using whole-cell voltage clamp. Injection of size-fractionated mRNA into Xenopus oocytes revealed that the current was most strongly expressed from the fraction containing mRNA of approximately 4-5 kb. Expression of this channel represents a starting point for the expression cloning of a novel class of K+ channels.
Department of Pharmacology and Toxicology, Medical College of Georgia, Augusta 30912.
D L
DL
Lewis
S R
SR
Ikeda
D
D
Aryee
R H
RH
Joho
D000818:Animals; D003001:Cloning, Molecular; D004553:Electric Conductivity; D015870:Gene Expression; D015640:Ion Channel Gating; D015471:Leukemia, Basophilic, Acute; D008564:Membrane Potentials; D011188:Potassium / Q000502:physiology; D015221:Potassium Channels / Q000235:genetics* / Q000502:physiology; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D014407:Tumor Cells, Cultured; D014982:Xenopus laevis
D015221:Potassium Channels; D012333:RNA, Messenger; D011188:Potassium