KTN (RCK) Domains Regulate K+ Channels and Transporters by Controlling the Dimer-Hinge Conformation

Tarmo P. Roosild, Samantha Castronovo, Samantha Miller, Chan Li, Tim Rasmussen, Wendy Bartlett, Banuri Gunasekera, Senyon Choe, Ian Rylance Booth

Research output: Contribution to journalArticlepeer-review

45 Citations (Scopus)


KTN (RCK) domains are nucleotide-binding folds that form the cytoplasmic regulatory complexes of various K+ channels and transporters. The mechanisms these proteins use to control their transmembrane pore-forming counterparts remains unclear despite numerous electrophysiological and structural studies. KTN (RCK) domains consistently crystallize as dimers within the asymmetric unit, forming a pronounced hinge between two Rossmann folds. We have previously proposed that modification of the hinge angle plays an important role in activating the associated membrane-integrated components of the channel or transporter. Here we report the structure of the C-terminal, KTN-bearing domain of the E. coli KefC K+ efflux system in association with the ancillary subunit, KefF, which is known to stabilize the conductive state. The structure of the complex and functional analysis of KefC variants reveal that control of the conformational flexibility inherent in the KTN dimer hinge is modulated by KefF and essential for regulation of KefC ion flux.

Original languageEnglish
Pages (from-to)893-903
Number of pages11
Issue number6
Early online date9 Jun 2009
Publication statusPublished - 10 Jun 2009


  • potassium-efflux system
  • Escherichia-Coli
  • crystal-structure
  • protein TRKA
  • ATP-binding
  • gating ring
  • in-vivo
  • KEFC
  • activation
  • mechanism


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