@article{00739b281e034f66b44f1125edc23273,
title = "Sodium and potassium competition in potassium-selective and non-selective channels",
abstract = "Potassium channels selectively conduct K +, primarily to the exclusion of Na +, despite the fact that both ions can bind within the selectivity filter. Here we perform crystallographic titration and single-channel electrophysiology to examine the competition of Na + and K + binding within the filter of two NaK channel mutants; one is the potassium-selective NaK2K mutant and the other is the non-selective NaK2CNG, a CNG channel pore mimic. With high-resolution structures of these engineered NaK channel constructs, we explicitly describe the changes in K + occupancy within the filter upon Na + competition by anomalous diffraction. Our results demonstrate that the non-selective NaK2CNG still retains a K + -selective site at equilibrium, whereas the NaK2K channel filter maintains two high-affinity K + sites. A double-barrier mechanism is proposed to explain K + channel selectivity at low K + concentrations.",
author = "Sauer, {David B.} and Weizhong Zeng and John Canty and Yeeling Lam and Youxing Jiang",
note = "Funding Information: We thank Nam Nguyen for critical review and discussion of this manuscript. We thank the beamline staff of the Advanced Photon Source and the Advanced Light Source for assistance in data collection. Use of the Advanced Photon Source, an Office of Science User Facility operated for the US Department of Energy (DOE) Office of Science by Argonne National Laboratory, was supported by the US DOE under contract number DE-AC02-06CH11357. The Berkeley Center for Structural Biology is supported in part by the National Institutes of Health, National Institute of General Medical Sciences and the Howard Hughes Medical Institute. The Advanced Light Source is supported by the Director, Office of Science, Office of Basic Energy Sciences, of the US Department of Energy under contract number DE-AC02-05CH11231. This work was supported in part by the Howard Hughes Medical Institute and by grants from the National Institute of Health (GM079179 to Y.J.), the Welch Foundation (Grant I-1578 to Y.J.) and D.B.S was supported by the NIH Training Grant (T32 GM008297).",
year = "2013",
doi = "10.1038/ncomms3721",
language = "English (US)",
volume = "4",
journal = "Nature communications",
issn = "2041-1723",
publisher = "Nature Publishing Group",
}