Abstract
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 language | English (US) |
---|---|
Pages (from-to) | 34-43 |
Number of pages | 10 |
Journal | Journal of Structural Biology |
Volume | 128 |
Issue number | 1 |
DOIs | |
State | Published - Dec 1 1999 |
Keywords
- Aquaporin-1
- Electron crystallography
- Membrane protein
- Three-dimensional structure
- Water channel
ASJC Scopus subject areas
- Structural Biology