SLC2A5

SLC2A5 is a human gene that encodes the glucose transporter 5 (GLUT5), a member of the solute carrier family 2 (SLC2), also known as the GLUT family. GLUT5 functions as a facilitative transporter that mediates the passive movement of fructose across cell membranes down its concentration gradient. It is not driven by sodium ions or direct energy input and does not efficiently transport glucose.

Expression and localization of GLUT5 are highest in the small intestine, particularly on the apical (luminal) membrane of enterocytes, where it enables dietary fructose uptake from the gut. It is also detected at lower levels in other tissues, including the kidney proximal tubules, and to varying extents in brain, testis, and other sites, with distribution that can differ among individuals.

Structure and mechanism: GLUT5 is a multi-pass transmembrane protein, typically predicted to contain 12 transmembrane helices, consistent with other GLUT transporters. The transporter operates via an alternating-access mechanism, switching between inward- and outward-facing conformations to shuttle fructose across the membrane.

Regulation and physiology: GLUT5 contributes to intestinal fructose absorption and renal fructose handling. Its expression and activity can be influenced by dietary fructose intake; it is not primarily regulated by insulin, unlike some glucose transporters.

Clinical significance: Impaired GLUT5 function or reduced expression can contribute to fructose malabsorption, a condition associated with gastrointestinal symptoms after fructose consumption. Hereditary fructose intolerance is caused by aldolase B deficiency, not SLC2A5. Variants affecting GLUT5 efficiency are a subject of ongoing research, and GLUT5-related disease remains relatively rare.

See also: SLC2 family, GLUT transporters.