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-42967
J Biol Chem 2010 Dec 31;28553:41982-92. doi: 10.1074/jbc.M110.101790.
Show Gene links Show Anatomy links

Identification of a residue in helix 2 of rice plasma membrane intrinsic proteins that influences water permeability.

Zhang M , Lü S , Li G , Mao Z , Yu X , Sun W , Tang Z , Long M , Su W .


???displayArticle.abstract???
Molecular selection, ion exclusion, and water permeation are well known regulatory mechanisms in aquaporin. Water permeability was found to be diverse in different subgroups of plasma membrane intrinsic proteins (PIPs), even though the residues surrounding the water holes remained the same across the subgroups. Upon homology modeling and structural comparison, a conserved Ala/Ile(Val) residue difference was identified in helix 2 that affected the conformation of the NPA region and consequently influenced the water permeability. The residue difference was found to be conservative within the two subgroups of PIPs in rice as well as in other plants. Functional tests further confirmed the prediction via site-directed mutagenesis where replacement of Ala(103) or Ala(102) in respective OsPIP1;1 or OsPIP1;3 with Val yielded 7.0- and 2.2-fold increases in water transportation, and substitution of Ile(98) or Val(95) in respective OsPIP2;3 or OsPIP2;7 with Ala resulted in 73 or 52% reduction of water transportation. Based on structural analyses and molecular dynamics simulations, we proposed that the difference in water permeability was attributed to the orientation variations of helix 2 that modified water-water and water-protein interactions.

???displayArticle.pubmedLink??? 20926385
???displayArticle.pmcLink??? PMC3009924
???displayArticle.link??? J Biol Chem



References [+] :
Beitz, Point mutations in the aromatic/arginine region in aquaporin 1 allow passage of urea, glycerol, ammonia, and protons. 2006, Pubmed, Xenbase