Bilirubin forms a monoglucuronide Authored: Jassal, B, 2005-02-23 15:02:50 Bilirubin is a breakdown product of heme, causing death if allowed to accumulate in the blood. It is highly lipophilic and thus requires conjugation to become more water soluble to aid excretion. UGT1A1 is the only enzyme that converts bilirubin to either a monoglucuronide or diglucuronide. Mutations of the UGT1A1 gene cause complete loss or partial activity for bilirubin glucuronidation. EC Number: 2.4.1.17 Edited: Jassal, B, 2010-05-27 GENE ONTOLOGYGO:0006789 Pubmed3082969 Pubmed8027054 Reactome Database ID Release 43159194 Reactome, http://www.reactome.org ReactomeREACT_22274 Reviewed: D'Eustachio, P, 2010-05-08 bilirubin + UDP-glucuronic acid => bilirubin monoglucuronide + UDP