Insulin-regulated facilitative hexose transporter that mediates the transport of glucose and fructose. Also able to mediate the transport of dehydroascorbate. D-glucose(out) = D-glucose(in) D-fructose(out) = D-fructose(in) L-dehydroascorbate(out) = L-dehydroascorbate(in) Inhibited by cytochalasin B. Interacts with AP2B1. Principally intracellular. May move between intracellular vesicles and the plasma membrane. The dileucine internalization motif is critical for intracellular sequestration. Highly expressed in testis, but not in testicular carcinoma. Lower amounts present in most other tissues. In testis, down-regulated by estrogen. Belongs to the major facilitator superfamily. Sugar transporter (TC 2.A.1.1) family. Glucose transporter subfamily.