Potential outer membrane protein component of a toxin-immunity protein module, which functions as a cellular contact-dependent growth inhibition (CDI) system. CDI modules allow bacteria to communicate with and inhibit the growth of closely related neighboring bacteria in a contact-dependent fashion. This protein may be required for secretion and assembly of the CdiA toxin protein. Probable member of a two partner secretion pathway (TPS) in which it mediates the secretion of CdiA. Belongs to the TPS (TC 1.B.20) family.