Cloning and functional expression of the cDNA encoding an inwardly‐rectifying potassium channel expressed in pancreatic β‐cells and in the brain

FEBS Letters

Sakura, H.¹  Gribble, F.¹  Ashford, M.J.³  Khan, R.N.²  Lee, K.²  Ashfield, R.¹  Rowe, I.C.M.²  Ashcroft, F.M.¹  Ämmälä, C.¹  Adelman, J.P.³  Blair, T.A.³  Proks, P.¹  Bond, C.T.³ 

[1] University Laboratory of Physiology, Parks Road, Oxford, OX1 3PT, UK;Department of Pharmacology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QJ, UK;Vollum Institute, Oregon Health Sciences University, Portland, OR 97201, USA

关键词: K-channel;    Inward rectifyer;    ATP-sensitive K-channel;    Pancreatic β-cell;    BIR1;   

DOI  :  10.1016/0014-5793(95)00497-W

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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.

【 授权许可】

Unknown