UDPGlc

UDPGlc, commonly written UDP-glucose, is the uridine diphosphate form of glucose and serves as an activated sugar donor in a wide range of biosynthetic reactions. It is produced in cells as the product of glucose-1-phosphate and UTP and is used by glycosyltransferases to transfer glucose units to acceptor molecules such as proteins, lipids, or polysaccharides.

Biosynthesis of UDPGlc is catalyzed by the enzyme UDP-glucose pyrophosphorylase (also called glucose-1-phosphate uridylyltransferase). The reaction is: glucose-1-phosphate plus UTP yields UDP-glucose and pyrophosphate (PPi). The hydrolysis of PPi by inorganic pyrophosphatase helps drive the reaction forward, favoring UDP-glucose formation. In many organisms, UDP-glucose can be interconverted with other sugar nucleotides by specialized enzymes, maintaining balanced pools for various biosynthetic needs.

Functions and biological roles of UDPGlc are diverse. In many eukaryotes, UDP-glucose provides glucose units for glycogen (or starch) biosynthesis via the action of glycogen synthase and related enzymes. It is also a precursor for the synthesis of UDP-glucuronic acid through oxidation by UDP-glucose dehydrogenase, a key step in the production of glycosaminoglycans and proteoglycans in animals. In plants and bacteria, UDP-glucose serves as a substrate for synthesis of structural and storage polysaccharides, including cellulose and various capsule or exopolysaccharides. It also participates in sucrose biosynthesis in plants, where UDP-glucose donates glucose units to form sucrose-6-phosphate.

UDPGlc is a central metabolite in carbohydrate metabolism, linking energy status to the production of diverse glycans and glycoconjugates across organisms.