Category: sugar
Aliases: D-Galactose, Brain sugar, Cerebrose
Aldohexose monosaccharide (C₆H₁₂O₆), a C-4 epimer of glucose and the constituent of lactose, raffinose and myelin galactolipids. Absorbed across the enterocyte apical membrane by Na⁺-coupled SGLT1 (shared with glucose) and exported basolaterally via GLUT2. Hepatic clearance proceeds through the Leloir pathway: galactokinase (GALK1) phosphorylates it to galactose-1-phosphate, which galactose-1-phosphate uridylyltransferase (GALT) converts with UDP-glucose to UDP-galactose (interconverted by UDP-galactose-4-epimerase, GALE) and glucose-1-phosphate, feeding glycogenesis and glycolysis. It is essentially non-insulinotropic acutely versus [[insulin]]-driving glucose. Loss-of-function GALT defines classic galactosemia; accumulated galactitol via aldose reductase drives cataract.
PO: 0.5h