The structure of aquaporin-1 at 4.5-Å resolution reveals short α- helices in the center of the monomer

Kaoru Mitsuoka, Kazuyoshi Murata, Thomas Walz, Teruhisa Hirai, Peter Agre, J. Bernard Heymann, Andreas Engel, Yoshinori Fujiyoshi

Research output: Contribution to journalArticlepeer-review

107 Scopus citations


Aquaporin-1 is a water channel found in mammalian red blood cells that is responsible for high water permeability of its membrane. Our electron crystallographic analysis of the three-dimensional structure of aquaporin-1 at 4.5-Å resolution confirms the previous finding that each subunit consists of a right-handed bundle of six highly tilted transmembrane helices that surround a central X-shaped structure. In our new potential map, the rod-like densities for the transmembrane helices show helically arranged protrusions, indicating the positions of side chains. Thus, in addition to the six transmembrane helices, observation of helically arranged side-chain densities allowed the identification of two short α-helices representing the two branches of the central X-shaped structure that extend to the extracellular and cytoplasmic membrane surfaces. The other two branches are believed to be loops connecting the short α-helix to a neighboring transmembrane helix. A pore found close to the center of the aquaporin-1 monomer is suggested to be the course of water flow with implications for the water selectivity.

Original languageEnglish (US)
Pages (from-to)34-43
Number of pages10
JournalJournal of Structural Biology
Issue number1
StatePublished - Dec 1 1999


  • Aquaporin-1
  • Electron crystallography
  • Membrane protein
  • Three-dimensional structure
  • Water channel

ASJC Scopus subject areas

  • Structural Biology


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