KINETIC-ANALYSIS OF GLUCOSE-TRANSPORT IN WILD-TYPE AND TRANSPORTER-DEFICIENT SACCHAROMYCES-CEREVISIAE STRAINS UNDER GLUCOSE REPRESSION AND DEREPRESSION

Glucose transport in Saccharomyces cerevisiae is under regulatory control by glucose. After transition from glucose repression to derepression, the affinity of facilitated glucose transport into the cells increases from K(m) values around 7 mM to 1-2 mM. This change is accompanied by a significant increase of V(m) under these conditions. Published glucose-transport data obtained from the transporter-deficient single mutants snf3, hxt2 and the double mutant snf3,hxt2 (Kruckeberg and Bisson, 1990) were evaluated by computer-assisted nonlinear regression analysis, which indicates that additional glucose transporters are encoded by other genes different from SNF3 and HXT2. Regulation of glucose transport under glucose repression and derepression requires the presence of the SNF3 gene.