title: Substrate recognition by a sucrose transporting protein.
abstract: Protoplasts derived from developing soybean cotyledons were used to study substrate recognition by a sucrose transporting protein in plant membranes. When used as alternate substrate inhibitors of [14C] sucrose influx, five different fructosyl-substituted sucrose derivatives, phenyl-alpha-D-glucopyranoside, and phenyl-alpha-D-thioglucopyranoside proved to bind effectively to the sucrose carrier-active site. These results are interpreted to indicate that a large portion of substrate recognition by this carrier may arise from the interaction of a relatively hydrophobic portion of the sucrose molecule and a hydrophobic region of the carrier protein binding site. Binding of phenyl-alpha-D-thioglucopyranosides in which various substitutions were made for the glucosyl hydroxyls shows that the glucosyl hydroxyls at positions 3, 4, and 6 are involved in substrate recognition by the carrier protein.
mesh_terms: D002352:Carrier Proteins / Q000378:metabolism*; D008958:Models, Molecular; D010940:Plant Proteins / Q000378:metabolism*; D013025:Glycine max / Q000032:analysis*; D013379:Substrate Specificity; D013395:Sucrose / Q000378:metabolism; D013865:Thioglycosides / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D010940:Plant Proteins; D013865:Thioglycosides; D013395:Sucrose