Download MendeleyMolecular Structure of the Human CFTR Ion Channel.
Liu, F., Zhang, Z., Csanady, L., Gadsby, D.C., Chen, J.(2017) Cell 169: 85-95.e8
- PubMed: 28340353
- DOI: https://doi.org/10.1016/j.cell.2017.02.024
- Primary Citation of Related Structures:
5UAK - PubMed Abstract:
The cystic fibrosis transmembrane conductance regulator (CFTR) is an ATP-binding cassette (ABC) transporter that uniquely functions as an ion channel. Here, we present a 3.9 Å structure of dephosphorylated human CFTR without nucleotides, determined by electron cryomicroscopy (cryo-EM). Close resemblance of this human CFTR structure to zebrafish CFTR under identical conditions reinforces its relevance for understanding CFTR function. The human CFTR structure reveals a previously unresolved helix belonging to the R domain docked inside the intracellular vestibule, precluding channel opening. By analyzing the sigmoid time course of CFTR current activation, we propose that PKA phosphorylation of the R domain is enabled by its infrequent spontaneous disengagement, which also explains residual ATPase and gating activity of dephosphorylated CFTR. From comparison with MRP1, a feature distinguishing CFTR from all other ABC transporters is the helix-loop transition in transmembrane helix 8, which likely forms the structural basis for CFTR's channel function.
Organizational Affiliation:
Laboratory of Membrane Biophysics and Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA; Tri-Institutional Training Program in Chemical Biology, The Rockefeller University, 1230 York Avenue, New York, NY 10065, USA.
