Estrone is conjugated into estrogen conjugates such as estrone sulfate and estrone glucuronide by sulfotransferases and glucuronidases, and can also be hydroxylated by cytochrome P450 enzymes into catechol estrogens such as 2-hydroxyestrone and 4-hydroxyestrone or into estriol.[1] Both of these transformations take place predominantly in the liver.[1] Estrone can also be reversibly converted into estradiol by 17β-HSD.[1]