Within the NapC/NirT family of cytochrome c proteins, some members, such as NapC <db_xref db="SWISSPROT" dbkey="P33932"/> and NirT <db_xref db="SWISSPROT" dbkey="P24038"/>, bind four haem groups, while others, such as TorC <db_xref db="SWISSPROT" dbkey="P33226"/>, bind five haems. This family aligns the common N-terminal region that contains four haem-binding C-X(2)-CH motifs. NapC/NirT cytochrome c, N-terminal