Functional selectivity for glycerol of the nodulin 26 subfamily of plant membrane intrinsic proteins.
The nodulin-like intrinsic protein (NIP) subfamily of water and solute channels in plants is named for nodulin 26 of legume nodules. Two NIPs, soybean nodulin 26 and Lotus japonicus LIMP2, show a distinct functional profile with a low intrinsic osmotic water permeability (P(f)) and the ability to flux uncharged polyols such as glycerol. NIPs have a conserved signature sequence within the 'aromatic/arginine' region that forms the selectivity filter for major intrinsic proteins. This sequence is a hybrid of glyceroporin and aquaporin residues as well as exhibiting substitutions unique to the NIP subfamily. Site-directed mutagenesis of a conserved tryptophan in helix 2 of LIMP2 shows that this is a major determinant of glycerol selectivity.
Department of Biochemistry and Cellular and Molecular Biology, The University of Tennessee, 37996, Knoxville, TN, USA.
Ian S
IS
Wallace
David M
DM
Wills
James F
JF
Guenther
Daniel M
DM
Roberts
D000595:Amino Acid Sequence; D020346:Aquaporins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005990:Glycerol / Q000378:metabolism*; D007473:Ion Channels / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism; D009994:Osmolar Concentration; D010539:Permeability; D010940:Plant Proteins / Q000737:chemistry / Q000378:metabolism*; D017354:Point Mutation; D014364:Tryptophan / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014867:Water / Q000378:metabolism
D020346:Aquaporins; D007473:Ion Channels; D008565:Membrane Proteins; D010940:Plant Proteins; C110065:major intrinsic protein, plant; C045625:nodulin; D014867:Water; D014364:Tryptophan; D005990:Glycerol