UGT2A3 is a phase II drug-metabolizing enzyme that catalyzes glucuronidation reactions to enhance elimination of endogenous and xenobiotic compounds 1. The enzyme demonstrates selective substrate specificity, primarily glucuronidating bile acids, particularly hyodeoxycholic acid at the 6-hydroxy position 1. UGT2A3 exhibits tissue-specific expression patterns, with highest levels in small intestine (160% of liver), colon (78% of liver), and adipose tissue (91% of liver), with protein expression being highest in small intestine compared to liver and kidney 12. The enzyme undergoes N-glycosylation and shows significant correlation between mRNA and protein levels in liver samples (r = 0.64, p < 0.001) 2. A common polymorphism (rs13128286) with 0.13 allele frequency in European-Americans results in amino acid change T497A, affecting enzyme kinetics 1. UGT2A3 is inducible by rifampicin through pregnane X receptor activation, increasing mRNA levels over 4.5-fold 1. In colorectal cancer, UGT2A3 expression correlates with favorable prognosis and CD8+ T cell infiltration, suggesting tumor suppressor functions 34. The enzyme also shows potential as a biomarker for inflammatory bowel disease therapeutic response 5.