New structural insights provide a different angle on steroid sulfatase action.

A central part of human sulfation pathways is the spatially and temporally controlled desulfation of biologically highly potent steroid hormones. The responsible enzyme - steroid sulfatase (STS) - is highly expressed in placenta and peripheral tissues, such as fat, colon, and the brain. The shape of this enzyme and its mechanism are probably unique in biochemistry. STS was believed to be a transmembrane protein, spanning the Golgi double-membrane by stem region formed by two extended internal alpha-helices. New crystallographic data however challenge this view. STS now is portraited as a trimeric membrane-associated complex. We discuss the impact of these results on STS function and sulfation pathways in general and we hypothesis that this new STS structural understanding suggests product inhibition to be a regulator of STS enzymatic activity. [Display omitted] • Steroid sulfatase (STS) is a central enzyme, regulating steroid hormone trafficking and action. • New structural data show this STS enzyme to form a trimeric complex, associated with membranes. • These findings may have implications for the mode-of-action of STS and its regulation by product inhibition. [ABSTRACT FROM AUTHOR]