Müllerian inhibiting substance (MIS), also named anti-Müllerian hormone (AMH), is a tissue-specific TGF-beta superfamily growth factor. Its expression is restricted to Sertoli cells of fetal and postnatal testis, and to granulosa cells of postnatal ovary. MIS is synthesized and secreted as a disulfide-linked homodimeric propeptide. Proteolytic cleavage is required to separate the N-terminal proregion from the C-terminal bioactive peptide. Both fragments remain associated in a non-covalent complex. The C-terminal sequence forms a cysteine knot via seven canonical cysteine residues found in TGF-beta superfamily members.