Assembles with botulinum neurotoxin type D (BoNT/D) and protects it against pH-mediated inactivation or protease activity at pH 2.6 (the pH of the animal gastrointestinal tract) but not at pH 6.0. The non-toxic component is necessary to maintain toxicity. Forms a highly interlocked heterodimer with botulinum neurotoxin type C at pH 6.0 but not at pH 7.5 (By similarity). Botulinum toxins are produced as progenitor toxins of large molecular sizes of 12S (M toxin) and 16S (L toxin). M toxin consists of a non-toxic, non-hemagglutinin component (NTNHA) and the neurotoxin (PubMed:8569530, PubMed:11713244, PubMed:17581814). L toxin consists of the M toxin and the 3 subcomponents of hemagglutinin (HA) (PubMed:8569530, PubMed:17581814). HA is composed of subcomponents of 70, 33, and 17 kDa. Erythrocyte agglutination occurs when the entire complex is assembled (PubMed:17581814). The stoichiometry of the whole complex has been modeled as one BoNT/D, one NTNHA, three HA-70, six HA-33 and three HA-17 (PubMed:17581814). Has 3 domains that are structurally very similar to those in BoNT/D; light chain (nLC, equivalent to the light chain), N-heavy chain (nHN) and C-heavy chain (nHC). This protein can also be encoded on a prophage. Belongs to the botulism non-toxic nonhemagglutinin family.