Click here to close Hello! We notice that you are using Internet Explorer, which is not supported by Xenbase and may cause the site to display incorrectly. We suggest using a current version of Chrome, FireFox, or Safari.
XB-ART-44149
Biophys J 2011 Oct 19;1018:1887-95. doi: 10.1016/j.bpj.2011.09.019.
Show Gene links Show Anatomy links

The structural pathway for water permeation through sodium-glucose cotransporters.

Sasseville LJ , Cuervo JE , Lapointe JY , Noskov SY .


???displayArticle.abstract???
Although water permeation across cell membranes occurs through several types of membrane proteins, the only permeation mechanism resolved at atomic scale is that through aquaporins. Crystallization of the Vibrio parahaemolyticus sodium-galactose transporter (vSGLT) allows investigation of putative water permeation pathways through both vSGLT and the homologous human Na-glucose cotransporter (hSGLT1) using computational methods. Grand canonical Monte Carlo and molecular dynamics simulations were used to stably insert water molecules in both proteins, showing the presence of a water-filled pathway composed of ∼100 water molecules. This provides a structural basis for passive water permeation that is difficult to reconcile with the water cotransport hypothesis. Potential-of-mean-force calculations of water going through the crystal structure of vSGLT shows a single barrier of 7.7 kCal mol(-1), in agreement with previously published experimental data for cotransporters of the SGLT family. Electrophysiological and volumetric experiments performed on hSGLT1-expressing Xenopus oocytes showed that the passive permeation pathway exists in different conformational states. In particular, experimental conditions that aim to mimic the conformation of the crystal structure displayed passive water permeability. These results provide groundwork for understanding the structural basis of cotransporter water permeability.

???displayArticle.pubmedLink??? 22004742
???displayArticle.pmcLink??? PMC3192982
???displayArticle.link??? Biophys J
???displayArticle.grants??? [+]


References [+] :
Baker, Protein structure prediction and structural genomics. 2001, Pubmed