XB-ART-19598FEBS Lett 1995 Jun 19;3671:61-6.
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Cloning and functional expression of the cDNA encoding an inwardly-rectifying potassium channel expressed in pancreatic beta-cells and in the brain.
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;). 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.
PubMed ID: 7601286
Article link: FEBS Lett
Species referenced: Xenopus
Genes referenced: birc5 kcnj6