| First Author | Takahashi N | Year | 1994 |
| Journal | J Biol Chem | Volume | 269 |
| Issue | 37 | Pages | 23274-9 |
| PubMed ID | 8083233 | Mgi Jnum | J:20168 |
| Mgi Id | MGI:68280 | Doi | 10.1016/s0021-9258(17)31649-6 |
| Citation | Takahashi N, et al. (1994) Molecular cloning and functional expression of cDNA encoding a second class of inward rectifier potassium channels in the mouse brain. J Biol Chem 269(37):23274-9 |
| abstractText | We have cloned a second class of inward rectifier potassium channels, designated MB-IRK2, from a mouse brain cDNA library. The amino acid sequence of this clone shares 70% identity with the mouse IRK1. Xenopus oocytes injected with cRNA derived from MB-IRK2 expressed a K+ current, which showed inward rectifying channel characteristics similar to the MB-IRK1 current. In contrast to the MB-IRK1 current, however, the MB-IRK2 current exhibited significant inactivation during hyperpolarizing pulses. In patch clamp experiments with 140 mM K+ in the pipette, the single channel conductance of MB-IRK2 was 34.2 +/- 2.1 picosiemens (n = 5), a value significantly larger than that of MB-IRK1 (22.2 +/- 3.0 picosiemens, n = 5). Consistent with the whole cell current, the steady-state open probability (Po) of the MB-IRK2 channel decreased with hyperpolarization, whereas that of the MB-IRK1 remained constant. Northern blot analysis revealed the mRNA for MB-IRK2 to be expressed in forebrain, cerebellum, heart, kidney, and skeletal muscle. In the brain, the abundance of mRNA for MB-IRK2 was much higher in cerebellum than in forebrain and vice versa in the case of MB-IRK1. These results demonstrate that the IRK family is composed of multiple genes, which may play heterogeneous functional roles in various organs, including the central nervous system. |
