Compromised ATP binding as a mechanism of phosphoinositide modulation of ATP‐sensitive K+ channels

FEBS Letters

Wang, Wenxia¹  Cui, Yijun¹  Wang, Congmiao¹  Wang, Kun¹  Fan, Zheng¹ 

[1] Department of Physiology, The University of Tennessee Health Science Center, 894 Union Avenue, Memphis, TN 38163, USA

关键词: Inwardly rectifying potassium channel;    Purification;    Photoaffinity labeling;    ATP analog;    Phosphoinositide;    KATP channels;    ATP-sensitive K+ channels;    PPI;    phosphoinositide;    2-N3-ATP-[γ]bio;    2-azidoadenosine 5′-triphosphate [γ]-biotin;    ATP-[γ]azidoanilide-bio;    adenosine 5′-triphosphate [γ]azidoanilide-biotin;   

DOI  :  10.1016/S0014-5793(02)03671-2

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

Inhibition of ATP-sensitive K⁺ (K_ATP) channels by ATP, a process presumably initiated by binding of ATP to the pore-forming subunit, Kir6.2, is reduced in the presence of phosphoinositides (PPIs). Previous studies led to the hypothesis that PPIs compromise ATP binding. Here, this hypothesis was tested using purified Kir6.2. We show that PPIs bind purified Kir6.2 in an isomer-specific manner, that biotinylated ATP analogs photoaffinity label purified Kir6.2, and that this labeling is weakened in the presence of PPIs. Patch-clamp measurements confirmed that these ATP analogs inhibited Kir6.2 channels, and that PPIs decreased the level of inhibition. These results indicate that interaction of PPIs with Kir6.2 impedes ATP-binding activity. The PPI regulation of ATP binding revealed in this study provides a putative molecular mechanism that is potentially pivotal to the nucleotide sensitivity of K_ATP channels.

【 授权许可】

Unknown