High-affinity glucose transporter. Is only indispensable for growth on low glucose-containing media, because S.cerevisiae possesses other sugar transporters. Repressed at high glucose concentrations. Glucose transport is thought to be mediated by two kinetically distinct systems, a glucose-repressible high-affinity system and a constitutive low-affinity system. Belongs to the major facilitator superfamily. Sugar transporter (TC 2.A.1.1) family.