Part of the ESX-1 specialized secretion system, which delivers several virulence factors to host cells during infection, including the key virulence factors EsxA (ESAT-6) and EsxB (CFP-10). Part of the ESX-1 / type VII secretion system (T7SS), which is composed of cytosolic and membrane components. The ESX-1 membrane complex is composed of EccB1, EccCa1, EccCb1, EccD1 and EccE1 (PubMed:19876390). Interacts with EspD (PubMed:16135231). Was identified as a high-confidence drug target. Belongs to the EccE family.