J. Biol. Chem., Vol. 261, Issue 26, 11986-11991, Sep, 1986
Substrate recognition by a sucrose transporting protein
WD Hitz, PJ Card and KG Ripp
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.