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. Essential for the elimination and detoxification of drugs, xenobiotics and endogenous compounds. Catalyzes the glucuronidation of endogenous steroid hormones such as androgens and estrogens. Produces dihydrotestosterone (DHT) diglucuronide from the DHT after two subsequent glucoronidation steps. Also catalyzes of the glucuronidation the isoflavones genistein, daidzein, glycitein, formononetin, biochanin A and prunetin, which are phytoestrogens with anticancer and cardiovascular properties. Involved in the glucuronidation of the AGTR1 angiotensin receptor antagonist caderastan, a drug which can inhibit the effect of angiotensin II. glucuronate acceptor + UDP-alpha-D-glucuronate = acceptor beta-D-glucuronoside + H(+) + UDP 17beta-estradiol + UDP-alpha-D-glucuronate = 17beta-estradiol 3-O-(beta-D-glucuronate) + H(+) + UDP 17alpha-estradiol + UDP-alpha-D-glucuronate = 17alpha-estradiol 3-O-(beta-D-glucuronate) + H(+) + UDP estrone + UDP-alpha-D-glucuronate = estrone 3-O-(beta-D-glucuronate) + H(+) + UDP 16alpha,17alpha-estriol + UDP-alpha-D-glucuronate = 16alpha,17alpha-estriol 3-O-(beta-D-glucuronate) + H(+) + UDP 2-hydroxy-17beta-estradiol + UDP-alpha-D-glucuronate = 2-hydroxy-17beta-estradiol 3-O-(beta-D-glucuronate) + H(+) + UDP 2-hydroxy-17beta-estradiol + UDP-alpha-D-glucuronate = 17beta-estradiol 2-O-(beta-D-glucuronate) + H(+) + UDP 2-hydroxyestrone + UDP-alpha-D-glucuronate = 2-hydroxyestrone 3-O-(beta-D-glucuronate) + H(+) + UDP 4-hydroxy-17beta-estradiol + UDP-alpha-D-glucuronate = 4-hydroxy-17beta-estradiol 3-O-(beta-D-glucuronate) + H(+) + UDP 4-hydroxy-17beta-estradiol + UDP-alpha-D-glucuronate = 17beta-estradiol 4-O-(beta-D-glucuronate) + H(+) + UDP 4-hydroxyestrone + UDP-alpha-D-glucuronate = 4-hydroxyestrone 3-O-(beta-D-glucuronate) + H(+) + UDP 4-hydroxyestrone + UDP-alpha-D-glucuronate = estrone 4-O-(beta-D-glucuronate) + H(+) + UDP 2-methoxy-17beta-estradiol + UDP-alpha-D-glucuronate = 2-methoxy-17beta-estradiol 3-O-(beta-D-glucuronate) + H(+) + UDP 2-methoxyestrone + UDP-alpha-D-glucuronate = 2-methoxyestrone 3-O-(beta-D-glucuronate) + H(+) + UDP 4-methoxy-17beta-estradiol + UDP-alpha-D-glucuronate = 4-methoxy-17beta-estradiol 3-O-(beta-D-glucuronate) + H(+) + UDP 4-methoxyestrone + UDP-alpha-D-glucuronate = 4-methoxyestrone 3-O-(beta-D-glucuronate) + H(+) + UDP 17beta-hydroxy-5alpha-androstan-3-one + UDP-alpha-D-glucuronate = 5alpha-dihydrotestosterone 17-O-(beta-D-glucuronate) + H(+) + UDP 5alpha-dihydrotestosterone 17-O-(beta-D-glucuronate) + UDP-alpha-D-glucuronate = 5alpha-dihydrotestosterone 17-O-[beta-D-glucuronosyl-(1->2)-glucuronate] + H(+) + UDP prunetin + UDP-alpha-D-glucuronate = prunetin-4'-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 mycophenolate + UDP-alpha-D-glucuronate = H(+) + mycophenolate 7-O-beta-D-glucuronide + UDP Homodimers. Homooligomer. Interacts with UGT1A1, UGT1A3, UGT1A4, UGT1A6, UGT1A7, UGT1A8, UGT1A9 and UGT1A10 to form heterodimers. UGT1A8 is one of the isoforms produced at the UGT1A complex locus. The UGT1A complex locus produces different isoforms based on alternative use of promoters, first exons and terminal exons. Belongs to the UDP-glycosyltransferase family.