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 specialized intracellular protease processing system. This C-terminal domain is embedded in the endoplasmic reticulum lumen, and binds to the N-terminal, transmembrane, SP_C, pfam08999, 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.