UDPglukuronotransferaasin

UDP-glucuronosyltransferases (UGTs) are a family of enzymes that catalyze the transfer of glucuronic acid from the donor molecule UDP-glucuronate to acceptor molecules such as drugs, bilirubin, and steroids. This reaction forms glucuronides, increasing solubility and enabling excretion in bile or urine. UGTs are predominantly expressed in the liver but are also found in other tissues, and are generally membrane-bound proteins located in the endoplasmic reticulum of cells.

Most mammalian UGTs belong to two main gene families, UGT1 and UGT2, with multiple isoforms that show tissue-specific expression and substrate preferences. The enzymes require UDP-glucuronate as the sugar donor and can glucuronidate a wide range of lipophilic substrates, including xenobiotics and endogenous compounds.

Mechanistically, UGTs transfer glucuronic acid to nucleophilic functional groups such as hydroxyl, carboxyl, amine or sulfur groups, forming glucuronides. The products are usually more polar and readily excreted. Regulation occurs at transcriptional level by nuclear receptors such as PXR and CAR, and by developmental and physiological factors; activity can be influenced by drug interactions, induction or inhibition of expression.

Clinical relevance: UGT-mediated metabolism affects drug clearance, bilirubin conjugation, and hormone regulation. Genetic polymorphisms, especially in UGT1A1, underlie conditions like Gilbert syndrome and neonatal jaundice, and can alter drug responses. Altered UGT activity can contribute to adverse drug reactions and drug–drug interactions.

Note: The term UDPglukuronotr... is not standard in English; it likely refers to UDP-glucuronosyltransferases (UGTs).