May be involved in the export of heme to the mitochondrion for the biogenesis of c-type cytochromes. The stop codon at position 233 is created by RNA editing. A stretch of 270 kb of the mitochondrial genome is duplicated within the centromere of chromosome 2 resulting in the duplication of the gene. The expression of the duplicated genes (At2g07681 and At2g07771) is demonstrated. Belongs to the CcmC/CycZ/HelC family. Was originally (PubMed:18299247) thought to belong to the ABC transporter family. Lacks the conserved ABC domain, which is one of the features of the ABC transporter family.