The Sulfatase Pathway for Estrogen Formation: Targets for the Treatment and Diagnosis of Hormone-Associated Tumors

Figure 3

Conjugation of estrone (E1) with sulfate by the estrogen sulfotransferases (SULT) results in the formation of inactive estrone sulfate (E1S). Sulfated estrone is reactivated by the steroid sulfatase (STS) which catalyzes the removal of sulphate, forming estrone (E1). The sulfuryl group donor for the sulfotransferase-catalyzed sulfation is 3′-phosphoadenosine 5′-phosphosulfate (PAPS). The enzymatic reaction requires the acceptor (R-OH) and the donor PAPS to bind to a sulfotransferase. PAPS is synthesized by PAPS-synthesizing enzymes (PAPSS1 and PAPSS2). 3′-phosphoadenosine 5′-phosphosulfate synthase (PAPSS) catalyzes the biosynthesis of PAPS, which serves as the sulfate donor (see [22]).