This domain is found at the C-terminal end of sulfatases and alkaline phosphatases from bacteria, eukaryotes and archaea, including N-sulphoglucosamine sulphohydrolase from humans (SGSH) and Bifunctional sulfatase/alpha-L-rhamnosidase from Formosa agariphila (P36_S1_25). It shows a four-stranded antiparallel beta-sheet, with four surrounding alpha-helices, followed by a C-terminal extension consisting of a small two-stranded antiparallel beta-sheet [1, 2].

1: A marine bacterial enzymatic cascade degrades the algal polysaccharide ulvan. Reisky L, Prechoux A, Zuhlke MK, Baumgen M, Robb CS, Gerlach N, Roret T, Stanetty C, Larocque R, Michel G, Song T, Markert S, Unfried F, Mihovilovic MD, Trautwein-Schult A, Becher D, Schweder T, Bornscheuer UT, Hehemann JH; Nat Chem Biol. 2019;15:803-812. PMID:31285597

2: Structure of sulfamidase provides insight into the molecular pathology of mucopolysaccharidosis IIIA. Sidhu NS, Schreiber K, Propper K, Becker S, Uson I, Sheldrick GM, Gartner J, Kratzner R, Steinfeld R; Acta Crystallogr D Biol Crystallogr. 2014;70:1321-1335. PMID:24816101