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Mechanism for selectivity-inactivation coupling in KcsA potassium channels.(BIOPHYSICS AND COMPUTATIONAL BIOLOGY)(Author abstract)(Report)

Cheng, Wayland W. L. ; Mccoy, Jason G. ; Thompson, Ameer N. ; Nichols, Colin G. ; Nimigean, Crina M.

Proceedings of the National Academy of Sciences of the United States, March 29, 2011, Vol.108(13), p.5272(6) [Tạp chí có phản biện]

ISSN: 0027-8424

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  • Nhan đề:
    Mechanism for selectivity-inactivation coupling in KcsA potassium channels.(BIOPHYSICS AND COMPUTATIONAL BIOLOGY)(Author abstract)(Report)
  • Tác giả: Cheng, Wayland W. L. ; Mccoy, Jason G. ; Thompson, Ameer N. ; Nichols, Colin G. ; Nimigean, Crina M.
  • Chủ đề: Prokaryotes -- Research ; Potassium Channels -- Physiological Aspects
  • Là 1 phần của: Proceedings of the National Academy of Sciences of the United States, March 29, 2011, Vol.108(13), p.5272(6)
  • Mô tả: Structures of the prokaryotic [K.sup.+] channel, KcsA, highlight the role of the selectivity filter carbonyls from the GYG signature sequence in determining a highly selective pore, but channels displaying this sequence vary widely in their cation selectivity. Furthermore, variable selectivity can be found within the same channel during a process called C-type inactivation. We investigated the mechanism for changes in selectivity associated with inactivation in a model [K.sup.+] channel, KcsA. We found that E71A, a noninactivating KcsA mutant in which a hydrogen-bond behind the selectivity filter is disrupted, also displays decreased [K.sup.-] selectivity. In E71A channels, [Na.sup.+] permeates at higher rates as seen with [sup.86][Rb.sup.+] and [sup.22][Na.sup.+] flux measurements and analysis of intracelluiar [Na.sup.-] block. Crystal structures of E71A reveal that the selectivity filter no longer assumes the "collapsed," presumed inactivated, conformation in low [K.sup.+], but a "flipped" conformation, that is also observed in high [K.sup.-], high [Na.sup.+], and even [Na.sup.+] only conditions. The data reveal the importance of the E71-D80 interaction in both favoring inactivation and maintaining high [K.sup.+] selectivity. We propose a molecular mechanism by which inactivation and [K.sup.+] selectivity are linked, a mechanism that may also be at work in other channels containing the canonical GYG signature sequence. doi: 10.1073/pnas.1014186108
  • Ngôn ngữ: English
  • Số nhận dạng: ISSN: 0027-8424

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