Modular Design of the Selectivity Filter Pore Loop in a Novel Family of Prokaryotic 'Inward Rectifier' (NirBac) channels

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  • Lejla Zubcevic
  • Shizhen Wang
  • Sun-Joo Lee
  • Colin G Nichols
  • Stephen J Tucker

Colleges, School and Institutes


Potassium channels exhibit a modular design with distinct structural and functional domains; in particular, a highly conserved pore-loop sequence that determines their ionic selectivity. We now report the functional characterisation of a novel group of functionally non-selective members of the prokaryotic 'inward rectifier' subfamily of K(+) channels. These channels share all the key structural domains of eukaryotic and prokaryotic Kir/KirBac channels, but instead possess unique pore-loop selectivity filter sequences unrelated to any other known ionic selectivity filter. The strikingly unusual architecture of these 'NirBac' channels defines a new family of functionally non-selective ion channels, and also provides important insights into the modular design of ion channels, as well as the evolution of ionic selectivity within this superfamily of tetrameric cation channels.


Original languageEnglish
Article number15305
JournalScientific Reports
Publication statusPublished - 16 Oct 2015