The MOSC (MOCO sulfurase C-terminal) domain is a superfamily of beta-strand-rich domains identified in the molybdenum cofactor sulfurase and several other proteins from both prokaryotes and eukaryotes. These MOSC domains contain an absolutely conserved cysteine and occur either as stand-alone forms such as Swiss:P32157, or fused to other domains such as NifS-like catalytic domain in Molybdenum cofactor sulfurase. The MOSC domain is predicted to be a sulfur-carrier domain that receives sulfur abstracted by the pyridoxal phosphate-dependent NifS-like enzymes, on its conserved cysteine, and delivers it for the formation of diverse sulfur-metal clusters.

1: MOSC domains: ancient, predicted sulfur-carrier domains, present in diverse metal--sulfur cluster biosynthesis proteins including Molybdenum cofactor sulfurases. Anantharaman V, Aravind L; FEMS Microbiol Lett 2002;207:55-61. PMID:11886751