The BRICHOS domain is about 100 amino acids long. It is found in a variety of proteins implicated in dementia, respiratory distress and cancer. Its exact function is unknown; roles that have been proposed for it include (a) in targeting of the protein to the secretory pathway, (b) intramolecular chaperone-like function, and (c) assisting the specialised intracellular protease processing system [1]. This C-terminal domain is embedded in the endoplasmic reticulum lumen, and binds to the N-terminal, transmembrane, SP_C, Pfam:PF08999, provided that it is in non-helical conformation. Thus the Brichos domain of proSP-C is a chaperone that induces alpha-helix formation of an aggregation-prone TM region [2].

1: BRICHOS: a conserved domain in proteins associated with dementia, respiratory distress and cancer. Sanchez-Pulido L, Devos D, Valencia A; Trends Biochem Sci 2002;27:329-332. PMID:12114016

2: The Brichos domain of prosurfactant protein C can hold and fold a transmembrane segment. Johansson H, Eriksson M, Nordling K, Presto J, Johansson J; Protein Sci. 2009;18:1175-1182. PMID:19472327