UDP glycosyltransferases (UGT) are a superfamily of enzymes that catalyzes the addition of the glycosyl group from a UTP-sugar to a small hydrophobic molecule. This family currently consist of:

• Mammalian UDP-glucoronosyl transferases (EC 2.4.1.17) (UDPGT) [1,2]. A large family of membrane-bound microsomal enzymes which catalyze the transfer of glucuronic acid to a wide variety of exogenous and endogenous lipophilic substrates. These enzymes are of major importance in the detoxification and subsequent elimination of xenobiotics such as drugs and carcinogens.
• A large number of putative UDPGT from Caenorhabditis elegans.
• Mammalian 2-hydroxyacylsphingosine 1-β-galactosyltransferase [3] (EC 2.4.1.45) (also known as UDP-galactose-ceramide galactosyltransferase). This enzyme catalyzes the transfer of galactose to ceramide, a key enzymatic step in the biosynthesis of galactocerebrosides, which are abundant sphingolipids of the myelin membrane of the central nervous system and peripheral nervous system.
• Plants flavonol O(3)-glucosyltransferase (EC 2.4.1.91). An enzyme [4] that catalyzes the transfer of glucose from UDP-glucose to a flavanol. This reaction is essential and one of the last steps in anthocyanin pigment biosynthesis.
• Plants limonoid glucosyltransferase (EC 2.4.1.210).
• Baculoviruses ecdysteroid UDP-glucosyltransferase (EC 2.4.1.-) [5] (egt). This enzyme catalyzes the transfer of glucose from UDP-glucose to ectysteroids which are insect molting hormones. The expression of egt in the insect host interferes with the normal insect development by blocking the molting process.
• Prokaryotic zeaxanthin glucosyl transferase (EC 2.4.1.-) (gene crtX), an enzyme involved in carotenoid biosynthesis and that catalyses the glycosylation reaction which converts zeaxanthin to zeaxanthin-β- diglucoside.
• Streptomyces macrolide glycosyltransferases (EC 2.4.1.-) [6]. These enzymes specifically inactivates macrolide anitibiotics via 2'-O-glycosylation using UDP-glucose.

These enzymes share a conserved domain of about 50 amino acid residues located in their C-terminal section and from which a pattern has been extracted to detect them.