Cytochrome c-type biogenesis protein CcmF (IPR003568)

Short name: Cyt_c_biogenesis_CcmF

Overlapping homologous superfamilies


Family relationships


Within mitochondria and bacteria, a family of related proteins is involved in the assembly of periplasmic c-type cytochromes: these include CycK [PMID: 7665469], CcmF [PMID: 7635817,PMID: 9043133], NrfE [PMID: 8057835] and CcbS [PMID: 8389979]. These proteins may play a role in guidance of apocytochromes and haem groups for their covalent linkage by the cytochrome-c-haem lyase. Members of the family are probably integral membrane proteins, with up to 16 predicted transmembrane (TM) helices.

The gene products of the hel and ccl loci have been shown to be required specifically for the biogenesis of c-type cytochromes in the Gram-negative photosynthetic bacterium Rhodobacter capsulatus. The ccl locus contains two genes, ccl1 and ccl2, each of which possesses typical signal sequences to direct them to the periplasm [PMID: 1310666]. Ccl1 is similar to proteins encoded by chloroplast and mitochondrial genes, suggesting analogous functions in these organelles. It is believed that the hel-encoded proteins are required for the export of haem to the periplasm, where it is subsequently ligated to the c-type apocytochromes [PMID: 1310666].

The CycK and CycL proteins of Bradyrhizobium japonicum share up to 53% amino acid sequence identity with R. capsulatus proteins Cc11 and Cc12 proteins, respectively. CycK and CycL proteins, which are encoded by the cycHJKL-cluster, may form part of a cytochrome c-haem lyase complex whose active site faces the periplasm [PMID: 7715601].

GO terms

Biological Process

GO:0017004 cytochrome complex assembly
GO:0015886 heme transport

Molecular Function

GO:0015232 heme transporter activity

Cellular Component

GO:0016020 membrane

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.