The structural basis of water permeation and proton exclusion in aquaporins (Review)

Dax Fu, Min Lu

Research output: Contribution to journalReview articlepeer-review

79 Scopus citations


Aquaporins (AQPs) represent a ubiquitous class of integral membrane proteins that play critical roles in cellular osmoregulations in microbes, plants and mammals. AQPs primarily function as water-conducting channels, whereas members of a sub-class of AQPs, termed aquaglyceroporins, are permeable to small neutral solutes such as glycerol. While AQPs facilitate transmembrane permeation of water and/or small neutral solutes, they preclude the conduction of protons. Consequently, openings of AQP channels allow rapid water diffusion down an osmotic gradient without dissipating electrochemical potentials. Molecular structures of AQPs portray unique features that define the two central functions of AQP channels: effective water permeation and strict proton exclusion. This review describes AQP structures known to date and discusses the mechanisms underlying water permeation, proton exclusion and water permeability regulation.

Original languageEnglish (US)
Pages (from-to)366-374
Number of pages9
JournalMolecular Membrane Biology
Issue number5-6
StatePublished - Sep 2007
Externally publishedYes


  • Aquaporin
  • Mechanisms underlying water permeation
  • Membrane permeability
  • Membrane protein
  • Protein structure

ASJC Scopus subject areas

  • Molecular Biology
  • Cell Biology


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