The GLUT protein family belongs to the solute carrier 2 family (SLC2) and is a member of the major facilitator superfamily of membrane transporters. The GLUT proteins have a fold consisting of two symmetrical six transmembrane helix (TM) bundle. In addition, the proteins contain 12 membrane-spanning domains, an N-linked glycosylation site, and intracellular NH₂ and COOH termini, and a several conserved residues and motifs designated “sugar transporter signatures”^1,2.

Fourteen GLUT isoforms have been identified and are divided into 3 different group classes based on sequence similarity and structural and functional characteristics. GLUT 5,7,9 and 11 belong to class ll group¹.

The GLUT transporters are uniporters, which facilitate the diffusion of monosaccharides like glucose and fructose across the cell membrane in a concentration-dependent manner. GLUT5 is specific to fructose and is primarily expressed in the small intestine, but lower levels were also detected in the brain, adipose tissue, kidney, testes and skeletal muscle. Several metabolic disorders and cancers are linked to increased GLUT5 expression².