Facilitative glucose transporter, which is responsible for constitutive or basal glucose uptake. Has a very broad substrate specificity; can transport a wide range of aldoses including both pentoses and hexoses. Most important energy carrier of the brain: present at the blood-brain barrier and assures the energy-independent, facilitative transport of glucose into the brain (By similarity). In association with BSG and NXNL1, promotes retinal cone survival by increasing glucose uptake into photoreceptors (By similarity). D-glucose(out) = D-glucose(in) The uptake of glucose is inhibited by cytochalasin B. Glucose uptake is increased in response to phorbol ester 12-O-tetradecanoylphorbol-13-acetate (TPA) treatment: TPA-induced glucose uptake requires phosphorylation at Ser-226. Found in a complex with ADD2, DMTN and SLC2A1. Interacts (via C-terminus cytoplasmic region) with DMTN. Interacts with SNX27; the interaction is required when endocytosed to prevent degradation in lysosomes and promote recycling to the plasma membrane. Interacts with GIPC (via PDZ domain). Interacts with STOM. Interacts with SGTA (via Gln-rich region) (By similarity). Interacts with BSG (By similarity). Detected in brain capillary (at protein level). Detected in brain capillary. Phosphorylation at Ser-226 by PKC promotes glucose uptake by increasing cell membrane localization. Belongs to the major facilitator superfamily. Sugar transporter (TC 2.A.1.1) family. Glucose transporter subfamily.