Category: biosynthesis
Branch of glucose metabolism that diverts F6P → UDP-N-acetylglucosamine (UDP-GlcNAc), the substrate for: (1) O-GlcNAc protein modification (analogous to phosphorylation, dynamic regulation of metabolic + transcription factors); (2) N-linked glycoprotein synthesis (ER); (3) glycosaminoglycan biosynthesis (hyaluronan, chondroitin, heparan sulfate). The committed step is GFAT (glutamine fructose-6-P aminotransferase). Flux is glucose-sensitive — diabetic hyperglycemia drives increased UDP-GlcNAc + increased O-GlcNAcylation, a proposed mechanism in diabetic vascular complications. GLUCOSAMINE supplementation enters at the F6P-amination step; clinical evidence for joint-disease effects is mixed.