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Cloning and functional expression of the cDNA encoding an inwardly‐rectifying potassium channel expressed in pancreatic β‐cells and in the brain
Author(s) -
Bond C.T.,
Ämmälä C.,
Ashfield R.,
Blair T.A.,
Gribble F.,
Khan R.N.,
Lee K.,
Proks P.,
Rowe I.C.M.,
Sakura H.,
Ashford M.J.,
Adelman J.P.,
Ashcroft F.M.
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00497-w
Subject(s) - kir6.2 , potassium channel , xenopus , complementary dna , diazoxide , microbiology and biotechnology , heterologous expression , biology , chemistry , protein subunit , biochemistry , biophysics , endocrinology , gene , insulin , recombinant dna
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 rcK ATP (K ATP ‐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 K ATP ‐1 suggests that BIR1 is a subunit of a brain and β‐cell K ATP 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.