Plays a central role in mitochondrial cytochrome c maturation. Probable component of a heme lyase complex involved in the reduction of apocytochrome c (PubMed:16236729). Forms a complex with CCMF proteins (CCMFC, CCMFN1 and CCMFN2) that performs the assembly of heme with c-type apocytochromes in mitochondria (PubMed:18644794). Interacts (via N-terminus) with CYTC-1 (PubMed:16236729). Interacts with CCMFN1 and CCMFN2 (PubMed:18644794). Embryonic lethality when homozygous. Arrest of embryo development at the torpedo stage. Belongs to the CcmH/CycL/Ccl2/NrfF family.