UGT2B4 is mainly involved in the glucuronidation of hyodeoxycholic acid, a bile acid, and catechol-estrogens, such as 17-epiestriol and 4-hydroxy-estrone.[8]
The expression of the UGT2B4 enzyme is upregulated by the farnesoid X receptor (FXR), a nuclear receptor which is activated by bile acids.[9] These same bile acids are substrates for the UGT2B4 enzyme. Hence upregulation of UGT2B4 by activated FXR provides a mechanism for the detection, conjugation and subsequent elimination of toxic bile acids.