Part of the ABC transporter complex CcmAB involved in the biogenesis of c-type cytochromes; once thought to export heme, this seems not to be the case, but its exact role is uncertain. Responsible for energy coupling to the transport system (By similarity). Heme chaperone required for the biogenesis of c-type cytochromes. Transiently binds heme delivered by CcmC and transfers the heme to apo-cytochromes in a process facilitated by CcmF and CcmH (By similarity). ATP + H2O + heme b(in) = ADP + H(+) + heme b(out) + phosphate In the N-terminal section; belongs to the ABC transporter superfamily. CcmA exporter (TC 3.A.1.107) family. In the C-terminal section; belongs to the CcmE/CycJ family. This sequence is a fusion of the duplicated copies ccmA2 and ccmE2, however, important parts of the proteins are missing and it is therefore probably not functional. Could be the product of a pseudogene.