A molecular modeling approach defines a new group of Nodulin 26-like aquaporins in plants.
The three-dimensional models built for the Nod26-like aquaporins all exhibit the typical alpha-helical fold of other aquaporins containing the two ar/R and NPA constriction filters along the central water channel. Besides these structural homologies, they readily differ with respect to the amino acid residues forming the ar/R selective filter. According to these discrepancies in both the hydrophilicity and pore size of the ar/R filter, Nod26-like aquaporins can be distributed in three subgroups corresponding to NIP-1, NIP-II and a third subgroup of Nod26-like aquaporins exhibiting a highly hydrophilic and widely open filter. However, all Nod26-like aquaporins display a bipartite distribution of electrostatic charges along the water channel with an electropositive extracellular vestibular portion followed by an electronegative cytosolic vestibular portion. The specific transport of water, non-ionic solutes (glycerol, urea, ammoniac), ions (NH4+) and gas (NH(3)) across the Nod26-like obviously depends on the electrostatic and conformational properties of their central water channel.
D000595:Amino Acid Sequence; D000641:Ammonia / Q000737:chemistry; D051397:Aquaglyceroporins / Q000737:chemistry / Q000378:metabolism*; D001692:Biological Transport; D003198:Computer Simulation; D003600:Cytosol / Q000737:chemistry / Q000378:metabolism; D007887:Fabaceae / Q000737:chemistry / Q000378:metabolism*; D005990:Glycerol / Q000737:chemistry; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D012997:Solvents / Q000737:chemistry*; D055672:Static Electricity; D014508:Urea / Q000737:chemistry; D014867:Water / Q000737:chemistry
D051397:Aquaglyceroporins; D008565:Membrane Proteins; D010940:Plant Proteins; D012997:Solvents; C045625:nodulin; D014867:Water; D000641:Ammonia; D014508:Urea; D005990:Glycerol