UDP-glucuronosyltransferase (UGT) that catalyzes phase II biotransformation reactions in which lipophilic substrates are conjugated with glucuronic acid to increase the metabolite's water solubility, thereby facilitating excretion into either the urine or bile (PubMed:12181437, PubMed:15470161, PubMed:18052087, PubMed:18004212, PubMed:18674515, PubMed:18719240, PubMed:20610558, PubMed:23360619). Essential for the elimination and detoxification of drugs, xenobiotics and endogenous compounds (PubMed:12181437, PubMed:18004212). Catalyzes the glucuronidation of endogenous estrogen hormone epiestradiol (PubMed:18719240). Also catalyzes the glucuronidation of the isoflavones genistein, daidzein, glycitein, formononetin, biochanin A and prunetin, which are phytoestrogens with anticancer and cardiovascular properties (PubMed:18052087). Involved in the glucuronidation of the AGTR1 angiotensin receptor antagonist caderastan, a drug which can inhibit the effect of angiotensin II (PubMed:18674515). Involved in the biotransformation of 7-ethyl-10-hydroxycamptothecin (SN-38), the pharmacologically active metabolite of the anticancer drug irinotecan (PubMed:12181437, PubMed:18004212, PubMed:20610558, PubMed:23360619). Also metabolizes mycophenolate, an immunosuppressive agent (PubMed:15470161). Lacks UGT glucuronidation activity but acts as a negative regulator of isoform 1. glucuronate acceptor + UDP-alpha-D-glucuronate = acceptor beta-D-glucuronoside + H(+) + UDP 17alpha-estradiol + UDP-alpha-D-glucuronate = 17alpha-estradiol 3-O-(beta-D-glucuronate) + H(+) + UDP mycophenolate + UDP-alpha-D-glucuronate = H(+) + mycophenolate 7-O-beta-D-glucuronide + UDP SN-38 + UDP-alpha-D-glucuronate = H(+) + SN-38 O-beta-D-glucuronide + UDP prunetin + UDP-alpha-D-glucuronate = prunetin-5-O-beta-D-glucuronide + UDP candesartan + UDP-alpha-D-glucuronate = candesartan O-beta-D-glucuronoside + UDP Some kinetic parameters were assessed using commercial enzymes, which may represent a mix of both active and inactive protein forms, and therefore modify the kinetic values. Homodimer (PubMed:17179145). Homooligomer (Probable). Interacts with UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A8, UGT1A9 and UGT1A10 to form heterodimers (PubMed:17179145). Isoform 1 interacts with isoform 2/i2 suggesting that oligomerization is involved in negative regulation of transferase activity by isoform 2. Isoform 1 also interacts with respective i2 isoforms of UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A8, UGT1A9 and UGT1A10 (PubMed:20610558). Liver and gastric tissue (PubMed:9271343). Isoform 1 and isoform 2 are expressed in esophagus. Neither isoform is expressed in liver, kidney, colon and small intestine (PubMed:18004212). There are four common allelic UGT1A7 variants which exhibit significant differences in catalytic activity towards 3-, 7-, and 9-hydroxy-benzo(a)pyrene. UGT1A7*3 exhibits a 5.8-fold lower relative Vmax compared to UGT1A7*1, whereas UGT1A7*2 and UGT1A7*4 have a 2.6- and 2.8-fold lower relative Vmax than UGT1A7*1, respectively, suggesting that these mutations confer slow glucuronidation phenotype. UGT1A7 isoform is part of the UGT1A complex locus which displays alternative use of promoters, first exons and terminal exons. The locus is defined by 13 first exons, which are alternatively spliced to 3 other common exons and 2 alternative terminal exons 5. From the 27 possible mRNA isoforms, 9 produce functionally active polypeptides (UGT1A1, 1A3, 1A4, 1A5, 1A6, 1A7, 1A8, 1A9 and 1A10) called isoforms 1 (i1). Use of an alternative exon 5 (5b) as terminal exon is leading to 9 additional alternatively spliced products termed isoforms i2 and which lack transferase activity. Belongs to the UDP-glycosyltransferase family.