FIGURE 1.

Glucose transport activities of the D340X series of mutants of Hxt7. The D340X series was created by replacing Asp³⁴⁰ of Hxt7 with each of the other 19 amino acids. KY73 cells expressing each of the D340X mutant transporters were grown to log phase at 30 °C in SMal(ura) medium, after which glucose transport activity was measured for 5 s at 30 °C with d-glucose at 0.1 or 20 mm as substrate. Transport activities were normalized by cell number and expressed as a percentage of the value for wild-type Hxt7. Individual diamonds represent mutant or wild-type Hxt7. Closed diamonds indicate mutants for which kinetic analysis was performed, whereas open diamonds denote those for which transport activity was too low for assessment of kinetic parameters. Data are means ± S.E. (n ≥ 3).