Lacks formylglycine generating activity and is unable to convert newly synthesized inactive sulfatases to their active form. Inhibits the activation of sulfatases by SUMF1. Homodimer and heterodimer with SUMF1. The non-canonical ER retention motif mediates retention of the protein in the endoplasmic reticulum. Belongs to the sulfatase-modifying factor family. Although strongly similar to formylglycine-generating enzyme, lacks the catalytic Cys residues that bind the catalytic copper. The catalytic copper is required to activate oxygen and catalyze oxidative C-H activation.