The M13 family of endopeptidases are zinc-metalloenzymes, the majority of which are type II integral membrane proteins. The best characterised of this family is vertebrate neprilysin, which has important roles in inactivating signalling peptides involved in modulating neuronal activity, blood pressure, the immune system and reproduction. Other family members are also known or predicted to have biological roles regulating peptide signalling. Insect genomes have an expanded set of M13 metalloendopeptidases. Some of these possess all four characterized motifs required for catalytic activity of vertebrate neprilysin (and are classed as NEPRILYSINS in FlyBase), though most lack one or more of these motifs are likely inactive peptidases (classed here as NEPRILYSIN-LIKE). (Adapted from
FBrf0204608.)