A kinetic analysis of D-xylose transport in Rhodotorula glutinis.
The kinetics of D-xylose transport were studied in Rhodotorula glutinis. Analysis of the saturation isotherm revealed the presence of at least two carriers for D-xylose in the Rhodotorula plasma membrane. These two carriers exhibited Km values differing by more than an order of magnitude. The low-Km carrier was repressed in rapidly growing cells and derepressed by starvation of the cells. Several hexoses were observed to inhibit D-xylose transport. In the studies reported here, the inhibitions produced by D-galactose and 2-deoxy-D-glucose were examined in some detail in order to define the interactions of these sugars with the D-xylose carriers. 2-Deoxy-D-glucose competitively inhibited both of the D-xylose carriers. In contrast, only the low-Km carrier was competitively inhibited by D-galactose.
D001693:Biological Transport, Active / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D003847:Deoxyglucose / Q000494:pharmacology; D005690:Galactose / Q000494:pharmacology; D007700:Kinetics; D003904:Mitosporic Fungi / Q000378:metabolism*; D012248:Rhodotorula / Q000378:metabolism*; D014994:Xylose / Q000378:metabolism*
D003847:Deoxyglucose; D014994:Xylose; D005690:Galactose