Bacteria of the Clostridium genus produce protein neurotoxins, which are complexes consisting of neurotoxin (NT), haemagglutinin (HA), nontoxic nonhaemagglutinin (NTNH), and RNA [1, 2]. The domain described here is found at the C-terminus of the NTNH component.

1: Clostridium botulinum and its neurotoxins: a metabolic and cellular perspective. Johnson EA, Bradshaw M; Toxicon 2001;39:1703-1722. PMID:11595633

2: Characterization of nicking of the nontoxic-nonhemagglutinin components of Clostridium botulinum types C and D progenitor toxin. Sagane Y, Watanabe T, Kouguchi H, Sunagawa H, Inoue K, Fujinaga Y, Oguma K, Ohyama T; J Protein Chem 2000;19:575-581. PMID:11233171