Referenced in: none

Automatically associated channels: Kir3.2 , Kir6.2

Title: Cloning and functional expression of the cDNA encoding an inwardly-rectifying potassium channel expressed in pancreatic beta-cells and in the brain.

Authors: C T Bond, C Ammälä, R Ashfield, T A Blair, F Gribble, R N Khan, K Lee, P Proks, I C Rowe, H Sakura

Journal, date & volume: FEBS Lett., 1995 Jun 19 , 367, 61-6

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/7601286

Abstract
A cDNA clone encoding an inwardly-rectifying K-channel (BIR1) was isolated from insulinoma cells. The predicted amino acid sequence shares 72% identity with the cardiac ATP-sensitive K-channel rcKATP (KATP-1;[6]). The mRNA is expressed in the brain and insulinoma cells. Heterologous expression in Xenopus oocytes produced currents which were K(+)-selective, time-independent and showed inward rectification. The currents were blocked by external barium and caesium, but insensitive to tolbutamide and diazoxide. In inside-out patches, channel activity was not blocked by 1 mM internal ATP. The sequence homology with KATP-1 suggests that BIR1 is a subunit of a brain and beta-cell KATP channel. However, pharmacological differences and the lack of ATP-sensitivity, suggest that if, this is the case, heterologous subunits must exert strong modulatory influences on the native channel.