UDPglucosa

UDP-glucose, or UDP-glucose, is an activated form of glucose used as a glycosyl donor in a wide range of biosynthetic reactions. It is a nucleotide sugar composed of uridine diphosphate (UDP) linked to glucose, functioning as a substrate for many glycosyltransferases that assemble polysaccharides, glycoproteins, and glycolipids.

Biosynthesis of UDP-glucose occurs through the action of UDP-glucose pyrophosphorylase, which catalyzes the reaction of uridine triphosphate (UTP) with glucose-1-phosphate to form UDP-glucose and pyrophosphate. The reaction is driven by hydrolysis of pyrophosphate. The enzyme is encoded by galU in bacteria and has plant and animal homologs. UDP-glucose can be further converted into other activated sugars, such as UDP-glucuronic acid by UDP-glucose dehydrogenase and UDP-galactose by UDP-glucose 4-epimerase, enabling interconversion among nucleotide sugars used in glycan biosynthesis.

Functions of UDP-glucose include serving as the glucose donor for glycosyltransferases that synthesize polysaccharides and glycoconjugates. In plants, it supplies glucose for cellulose and callose biosynthesis. In microorganisms, it supports exopolysaccharide production and other cell-wall components. It also participates in pathways such as trehalose synthesis in bacteria and fungi, and provides UDP-glucuronate for detoxification and structural polysaccharides in other organisms.

Biological significance of UDP-glucose lies in its central role in carbohydrate metabolism and cell-wall biosynthesis. As a key donor sugar, its availability links cellular energy status to the capacity to produce glycans essential for structural integrity, signaling, and interactions, across bacteria, fungi, plants, and animals.