|PROSITE documentation PDOC00169 [for PROSITE entry PS51007]|
In proteins belonging to the c-type cytochrome family , the heme group is covalently attached by thioether bonds to two conserved cysteine residues located in the cytochrome c center. Cytochromes c typically function in electron transfer, but c-type cytochrome centers are also found in the active sites of many enzymes, and in eukaryotic cells, cytochrome c has also a role in apoptosis .
The known structures of c-type cytochromes have six different classes of fold. Of these, four are unique to c-type cytochromes . The different folds are detailed in the example list below.
The consensus sequence for the cytochrome c center is Cys-x-x-Cys-His, where the histidine residue is one of the two axial ligands of the heme iron . This arrangement is shared by all proteins known to belong to the cytochrome c family, which presently includes:
Multiheme proteins (prokaryotes). They are frequently associated with electron-transport processes within the nitrogen and sulphur cycles:
To recognize c-type cytochrome family proteins we have developed 4 profiles. The first one recognizes all mono-heme cytochrome c proteins (except class II and f-type cytochromes). The second one recognizes cytochrome c that binds more than one heme group. The third one recognizes class II cytochrome c and the fourth one is directed against cytochrome f family.Note:
These profiles replace a pattern which specificity was inadequate.Last update:
August 2004 / Pattern removed, profiles added and text revised.
PROSITE methods (with tools and information) covered by this documentation:
|Title||The structure, function and evolution of cytochromes.|
|Source||Prog. Biophys. Mol. Biol. 45:1-56(1985).|
|2||Authors||Martinou J.-C. Desagher S. Antonsson B.|
|Title||Cytochrome c release from mitochondria: all or nothing.|
|Source||Nat. Cell Biol. 2:E41-E43(2000).|
|3||Authors||Allen J.W. Daltrop O. Stevens J.M. Ferguson S.J.|
|Title||C-type cytochromes: diverse structures and biogenesis systems pose evolutionary problems.|
|Source||Philos. Trans. R. Soc. Lond., B, Biol. Sci. 358:255-266(2003).|
|4||Authors||Barker P.D. Ferguson S.J.|
|Title||Still a puzzle: why is haem covalently attached in c-type cytochromes?|