Summary: Class III cytochrome C family
This is the Wikipedia entry entitled "Cytochrome c family". More...
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Cytochrome c family Edit Wikipedia article
Structure of cytochrome c2 from Rhodopseudomonas viridis.
atomic structure of a cytochrome c' with an unusual ligand-controlled dimer dissociation at 1.8 angstroms resolution
|Class III cytochrome C family|
sulfate respiration in desulfovibrio vulgaris hildenborough: structure of the 16-heme cytochrome c hmca at 2.5 a resolution and a view of its role in transmembrane electron transfer
Cytochromes c (cytC) are electron-transfer proteins having one or several heme c groups, bound to the protein by one or, more generally, two thioether bonds involving sulphydryl groups of cysteine residues. The fifth haem iron ligand is always provided by a histidine residue. Cytochromes c possess a wide range of properties and function in a large number of different redox processes. The founding member of this family is mitochondrial cytochrome c.
Ambler recognized four classes of cytC.
- Class I includes the low-spin soluble cytC of mitochondria and bacteria, with the haem-attachment site towards the N-terminus, and the sixth ligand provided by a methionine residue about 40 residues further on towards the C-terminus. On the basis of sequence similarity, class I cytC were further subdivided into five classes, IA to IE. Class IB includes the eukaryotic mitochondrial cytC and prokaryotic 'short' cyt c2 exemplified by Rhodopila globiformis cyt c2; class IA includes 'long' cyt c2, such as Rhodospirillum rubrum cyt c2 and Aquaspirillum itersonii cytc-550, which have several extra loops by comparison with class IB cytC.
- Class II includes the high-spin cytC' and a number of low-spin cytochromes, e.g. cyt c-556. The haem-attachment site is close to the C terminus. The cytC' are capable of binding such ligands as CO, NO or CN(-), albeit with rate and equilibrium constants 100 to 1,000,000-fold smaller than other high-spin haemoproteins. This, coupled with its relatively low redox potential, makes it unlikely that cytC' is a terminal oxidase. Thus cytC' probably functions as an electron transfer protein. The 3D structures of a number of cytC' have been determined. The molecule usually exists as a dimer, each monomer folding as a four-alpha-helix bundle incorporating a covalently-bound haem group at the core. The Chromatium vinosum cytC' exhibits dimer dissociation upon ligand binding.
- Class III comprises the low redox potential multiple haem cytochromes: cyt C7 (trihaem), C3 (tetrahaem), and high-molecular-weight cytC, HMC (hexadecahaem), with only 30-40 residues per haem group. The haem c groups, all bis-histidinyl coordinated, are structurally and functionally nonequivalent and present different redox potentials in the range 0 to -400 mV. The 3D structures of a number of cyt C3 proteins have been determined. The proteins consist of 4-5 alpha-helices and 2 beta-strands wrapped around a compact core of four non-parallel haems, which present a relatively high degree of exposure to the solvent. The overall protein architecture, haem plane orientations and iron-iron distances are highly conserved.
- Class IV includes complex proteins containing other prosthetic groups besides haem c, such as flavocytochromes c and cytochromes cd.
Human proteins containing this domain
- Miki K, Sogabe S, Uno A, et al. (May 1994). "Application of an automatic molecular-replacement procedure to crystal structure analysis of cytochrome c2 from Rhodopseudomonas viridis". Acta Crystallogr. D Biol. Crystallogr. 50 (Pt 3): 271–5. doi:10.1107/S0907444993013952. PMID 15299438.
- Moore GR, Pettigrew GW (1987). pp. –. Missing or empty
- Ambler RP (1991). "Sequence variability in bacterial cytochromes c". Biochim. Biophys. Acta 1058 (1): 42–47. doi:10.1016/S0005-2728(05)80266-X. PMID 1646017.
- Kassner RJ (May 1991). "Ligand binding properties of cytochromes c'". Biochim. Biophys. Acta 1058 (1): 8–12. doi:10.1016/s0005-2728(05)80257-9. PMID 1646027.
- Moore GR (May 1991). "Bacterial 4-alpha-helical bundle cytochromes". Biochim. Biophys. Acta 1058 (1): 38–41. doi:10.1016/s0005-2728(05)80265-8. PMID 1646016.
- Ren Z, Meyer T, McRee DE (November 1993). "Atomic structure of a cytochrome c' with an unusual ligand-controlled dimer dissociation at 1.8 A resolution". J. Mol. Biol. 234 (2): 433–45. doi:10.1006/jmbi.1993.1597. PMID 8230224.
- Coutinho IB, Xavier AV (1994). "Tetraheme cytochromes". Meth. Enzymol. 243: 119–40. doi:10.1016/0076-6879(94)43011-X. PMID 7830606.
Class III cytochrome C family Provide feedback
No Pfam abstract.
Internal database links
|SCOOP:||Cytochrom_NNT DHC Paired_CXXCH_1|
|Similarity to PfamA using HHSearch:||Cytochrome_C7 Cytochrom_c3_2|
External database links
This tab holds annotation information from the InterPro database.
InterPro entry IPR020942Cytochromes c (cytC) can be defined as electron-transfer proteins having one or several haem c groups, bound to the protein by one or, more generally, two thioether bonds involving sulphydryl groups of cysteine residues. The fifth haem iron ligand is always provided by a histidine residue. CytC possess a wide range of properties and function in a large number of different redox processes [PUBMED:9293186].
Ambler [PUBMED:1646017] recognised four classes of cytC.
Class III comprises the low redox potential multiple haem cytochromes: cyt C7 (trihaem), C3 (tetrahaem), and high-molecular-weight cytC, HMC (hexadecahaem), with only 30-40 residues per haem group. The haem c groups, all bis-histidinyl coordinated, are structurally and functionally nonequivalent and present different redox potentials in the range 0 to -400 mV [PUBMED:7830606]. The 3D structures of a number of cyt C3 proteins have been determined. The proteins consist of 4-5 alpha-helices and 2 beta-strands wrapped around a compact core of four non-parallel haems, which present a relatively high degree of exposure to the solvent. The overall protein architecture, haem plane orientations and iron-iron distances are highly conserved [PUBMED:7830606].
The mapping between Pfam and Gene Ontology is provided by InterPro. If you use this data please cite InterPro.
|Molecular function||electron carrier activity (GO:0009055)|
|heme binding (GO:0020037)|
- the number of sequences which exhibit this architecture
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This family includes cytochromes that contain multiple CxxCH motifs.
The clan contains the following 11 members:CytoC_RC Cytochrom_c3_2 Cytochrom_C552 Cytochrom_CIII Cytochrom_NNT Cytochrome_C554 Cytochrome_C7 GSu_C4xC__C2xCH Multi-haem_cyto NapB Paired_CXXCH_1
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Curation and family details
|Author:||Mian N, Bateman A|
|Number in seed:||24|
|Number in full:||410|
|Average length of the domain:||94.70 aa|
|Average identity of full alignment:||21 %|
|Average coverage of the sequence by the domain:||46.57 %|
|HMM build commands:||
build method: hmmbuild -o /dev/null HMM SEED
search method: hmmsearch -Z 23193494 -E 1000 --cpu 4 HMM pfamseq
|Family (HMM) version:||11|
|Download:||download the raw HMM for this family|
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For those sequences which have a structure in the Protein DataBank, we use the mapping between UniProt, PDB and Pfam coordinate systems from the PDBe group, to allow us to map Pfam domains onto UniProt sequences and three-dimensional protein structures. The table below shows the structures on which the Cytochrom_CIII domain has been found. There are 90 instances of this domain found in the PDB. Note that there may be multiple copies of the domain in a single PDB structure, since many structures contain multiple copies of the same protein seqence.
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