Molecular structure of the glibenclamide binding site of the β‐cell KATP channel

FEBS Letters

Mikhailov, Michael V¹  Mikhailova, Ellina A¹  Ashcroft, Stephen J.H¹ 

[1] Nuffield Department of Clinical Laboratory Sciences, John Radcliffe Hospital, Headington, Oxford OX3 9DU, UK

关键词: Potassium channel;    Sulfonylurea receptor;    Baculovirus;    ATP binding cassette protein;    SUR1/ABCC8;   

DOI  :  10.1016/S0014-5793(01)02538-8

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

We have investigated the structure of the glibenclamide binding site of pancreatic β-cell ATP-sensitive potassium (K_ATP) channels. K_ATP channels are a complex of four pore-forming Kir6.2 subunits and four sulfonylurea receptor (SUR1) subunits. SUR1 (ABCC8) belongs to the ATP binding cassette family of proteins and has two nucleotide binding domains (NBD1 and NBD2) and 17 putative transmembrane (TM) sequences. Co-expression in a baculovirus expression system of two parts of SUR1 between NBD1 and TM12 leads to restoration of glibenclamide binding activity, whereas expression of either individual N- or C-terminal part alone gave no glibenclamide binding activity, confirming a bivalent structure of the glibenclamide binding site. By using N-terminally truncated recombinant proteins we have shown that CL3 – the cytosolic loop between TM5 and TM6 – plays a key role in formation of the N-terminal component of the glibenclamide binding site. Analysis of deletion variants of the C-terminal part of SUR1 showed that CL8 – the cytosolic loop between TM15 and TM16 – is the only determinant for the C-terminal component of the glibenclamide binding site. We suggest that in SUR1 in the native K_ATP channel close proximity of CL3 and CL8 leads to formation of the glibenclamide binding site.

【 授权许可】

Unknown