Formylglycine-generating enzyme
Formylglycine-generating enzyme (FGE), located at 3p26.1 in humans, is the name for an enzyme present in the endoplasmic reticulum that catalyzes the conversion of cysteine to formylglycine (fGly). There are two main classes of FGE, aerobic and anaerobic. FGE activates sulfatases, which are essential for the degradation of sulfate esters. The catalytic activity of sulfatases is dependent upon a formylglycine (sometimes called oxoalanine) residue in the active site. Aerobic. The aerobic enzyme has a structure homologous to the complex alpha/beta topology found in the gene product of human sulfatase-modifying factor 1 (SUMF1). Aerobic FGE  converts a cysteine residue in the highly conserved consensus sequence CXPXR to fGly. To do so, FGE “activates” its target by utilizing mononuclear copper. The substrate first binds to copper, increasing reactivity of the substrate-copper complex with oxygen. Activation is then accomplished through oxidation of a cysteine residue in the substrate-copper complex. Due to the nature of this reaction, FGE is termed a “copper-dependent metalloenzyme. Anaerobic. The most well-studied anaerobic FGE is the bacterial AtsB, an iron-sulfur cluster containing enzyme present in "Klebsiella pneumoniae", that is able to convert either cysteine or serine to fGly  with a distinctly different mechanism than the aerobic form. While AtsB can convert either, its activity increases four fold when in the presence of cysteine over serine. AtsB is 48% similar to an enzyme present in "Clostridium perfringens". Both enzymes possess the CxCxC motif unique to the radical S-adenosyl methionine superfamily and are able to use a reduction reaction to cleave S-adenosyl methionine. These two enzymes fall into a larger group called the anaerobic Sulfatase Maturing Enzymes, which are able to convert cysteine into fGly without the use of oxygen. Protein domain. In molecular biology, "formylglycine-generating enzyme