title: K(+) preference at the NaK channel entrance revealed by fluorescence lifetime and anisotropy analysis of site-specifically incorporated (7-hydroxycoumarin-4-yl)ethylglycine.
abstract: The fluorescent unnatural amino acid, (7-hydroxycoumarin-4-yl)ethylglycine (HC), was site-specifically incorporated at the Phe69 site, close to the entrance of the selectivity filter of the NaK channel. Decreased fluorescence lifetime and elevated time-resolved anisotropy of NaK-F69HC in buffers with high K(+)/Na(+) molar ratios indicated the K(+) preference at the entrance of the NaK channel, consistent with previous crystal structure results of the NaK channel.
authors.affiliation: High Magnetic Field Laboratory, Chinese Academy of Sciences, and School of Life Sciences, University of Science and Technology of China, Hefei 230026, Anhui, P. R. China. zlhustc@ustc.edu.cn cltian@ustc.edu.cn.
authors.forename: Sanling
authors.initials: S
authors.lastname: Liu
authors.forename: Pei
authors.initials: P
authors.lastname: Lv
authors.forename: Dong
authors.initials: D
authors.lastname: Li
authors.forename: Xiaoqi
authors.initials: X
authors.lastname: Guo
authors.forename: Bo
authors.initials: B
authors.lastname: Zhang
authors.forename: Mu
authors.initials: M
authors.lastname: Yu
authors.forename: Dandan
authors.initials: D
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Xiong
authors.forename: Longhua
authors.initials: L
authors.lastname: Zhang
authors.forename: Changlin
authors.initials: C
authors.lastname: Tian
mesh_terms: D001409:Bacillus cereus; D001426:Bacterial Proteins / Q000502:physiology* / Q000648:ultrastructure; D005454:Fluorescence Polarization; D005998:Glycine / Q000031:analogs & derivatives* / Q000737:chemistry / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D011188:Potassium / Q000502:physiology*; D015221:Potassium Channels / Q000502:physiology* / Q000648:ultrastructure; D014468:Umbelliferones / Q000737:chemistry*
chemical_list: C522545:(7-hydroxycoumarin-4-yl) ethylglycine; D001426:Bacterial Proteins; D015221:Potassium Channels; D014468:Umbelliferones; C107790:prokaryotic potassium channel; D011188:Potassium; D005998:Glycine