Glucose Transporter 3 (GLUT3)

GLUT3 is a high-affinity isoform of Type I glucose transporter expressed mostly in neurons where it is believed to be the main glucose transporter isoform, and in the placenta. GLUTs are integral membrane proteins which contain 12 membrane spanning helices with both the amino and carboxyl termini exposed on the cytoplasmic side of the plasma membrane. GLUT proteins transport glucose and related hexoses according to a model of alternate conformation, which predicts that the transporter exposes a single substrate binding site toward either the outside or the inside of the cell. Binding of glucose to one site provokes a conformational change associated with transport, and releases glucose to the other side of the membrane.