Glucose transporters (GLUTs) and other similar sugar transporters of the Major Facilitator Superfamily
This family is composed of glucose transporters (GLUTs) and other sugar transporters including fungal hexose transporters (HXT), bacterial xylose transporter (XylE), plant sugar transport proteins (STP) and polyol transporters (PLT), H(+)-myo-inositol cotransporter (HMIT), and similar proteins. GLUTs, also called Solute carrier family 2, facilitated glucose transporters (SLC2A), are a family of proteins that facilitate the transport of hexoses such as glucose and fructose. There are fourteen GLUTs found in humans; they display different substrate specificities and tissue expression. They have been categorized into three classes based on sequence similarity: Class 1 (GLUTs 1-4, 14); Class 2 (GLUTs 5, 7, 9, and 11); and Class 3 (GLUTs 6, 8, 10, 12, and HMIT). GLUT proteins are comprised of about 500 amino acid residues, possess a single N-linked oligosaccharide, and have 12 transmembrane segments. The GLUT-like family belongs to the Major Facilitator Superfamily (MFS) of membrane transport proteins, which are thought to function through a single substrate binding site, alternating-access mechanism involving a rocker-switch type of movement.