Human estrone sulfatase (ES) is responsible for maintaining high levels of the active estrogen in tumor cells. ES catalyzes the hydrolysis of E1 sulfate, which is a component of the three-enzyme system that has been implicated in intracrine biosynthesis of estradiol. It is associated with the membrane of the endoplasmic reticulum (ER). The structure of ES consisting of two antiparallel alpha helices that protrude from the roughly spherical molecule. These highly hydrophobic helices anchor the functional domain on the membrane surface facing the ER lumen.
Jiyao W et al.(2023). "The conserved domain database in 2023.",