title: Insights into the stimulatory mechanism of 2-aminoethoxydiphenyl borate on TREK-2 potassium channel.
abstract: 2-Aminoethoxydiphenyl borate (2-APB) has been recently identified as a common agonist of TWIK-related K(+) channel (TREK)/TRAAK channels, a subfamily of two-pore domain K(+) (K2P) channels. TREK-2 displays much higher sensitivity to 2-APB compared with TREK-1, despite that these two channels share the highest homology among K2P members. However, the structural basis for their difference in response to 2-APB still remains unknown. Here we identified that the cytosolic C-terminus (Ct) domain plays a dominant role in controlling the stimulatory effects of 2-APB on TREK-2 channel. The distal Ct region negatively regulates the effect of 2-APB, while the proximal Ct is sufficient to evoke the full 2-APB activation of the channel. Further mapping within the proximal Ct revealed that His368 is required for 2-APB activation, and the cooperation of the other non-conserved residues is also necessary. We also identified a secondary active site for 2-APB, which is located at the bottom of the transmembrane segment M2. Finally, we demonstrated that key residues or domains required for 2-APB activation are not involved in the gating mechanism of the selectivity filter. In summary, we reveal a unique modulatory model of TREK-2-Ct that distinguishes it from TREK-1 in high sensitivity to 2-APB. The cooperation of the non-conserved residues within the proximal Ct of TREK-2 plays a dominant role in the 2-APB-induced channel opening, whereas the distal Ct negatively regulates the process.
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China; State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
authors.forename: R-G
authors.initials: RG
authors.lastname: Zhuo
authors.affiliation: State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
authors.forename: X-Y
authors.initials: XY
authors.lastname: Liu
authors.affiliation: State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
authors.forename: S-Z
authors.initials: SZ
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
authors.forename: X-L
authors.initials: XL
authors.lastname: Wei
authors.affiliation: State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China.
authors.forename: J-Q
authors.initials: JQ
authors.lastname: Zheng
authors.affiliation: Department of Pharmacology, School of Pharmaceutical Sciences, Southern Medical University, Guangzhou 510515, China. Electronic address: jpx@smu.edu.cn.
authors.forename: J-P
authors.initials: JP
authors.lastname: Xu
authors.affiliation: State Key Laboratory of Toxicology and Medical Countermeasures, Department of Biochemical Pharmacology, Beijing Institute of Pharmacology and Toxicology, Beijing 100850, China. Electronic address: maxyer22@yahoo.com.
authors.forename: X-Y
authors.initials: XY
authors.lastname: Ma
mesh_terms: D000818:Animals; D001896:Boron Compounds / Q000494:pharmacology*; D020134:Catalytic Domain; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D049990:Membrane Transport Modulators / Q000494:pharmacology*; D009154:Mutation; D009865:Oocytes; D018408:Patch-Clamp Techniques; D024683:Potassium Channels, Tandem Pore Domain / Q000235:genetics / Q000378:metabolism*; D014982:Xenopus laevis
chemical_list: D001896:Boron Compounds; C503438:KCNK10 protein, human; D049990:Membrane Transport Modulators; D024683:Potassium Channels, Tandem Pore Domain; C103742:potassium channel protein TREK-1; C109986:2-aminoethoxydiphenyl borate
keywords: 2-APB; C-terminal domain; TREK-1; TREK-2; gate mechanism; selectivity filter