Part of the ecpRABCDE operon, which encodes the E.coli common pilus (ECP). ECP is found in both commensal and pathogenic strains and plays a dual role in early-stage biofilm development and host cell recognition (By similarity). Negatively regulated by H-NS. Positively regulated by IHF and EcpR (By similarity). Not expressed under classical laboratory conditions, but is functional when constitutively expressed. Belongs to the EcpC/MatD family.