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a domain/subunit of cytochrome bc1 complex (Ubiquinol-cytochrome c reductase) superfamily

SCOP classification
Root:   SCOP hierarchy in SUPERFAMILY [ 0] (11)
Class:   Membrane and cell surface proteins and peptides [ 56835] (58)
Fold:   a domain/subunit of cytochrome bc1 complex (Ubiquinol-cytochrome c reductase) [ 81649]
Superfamily:   a domain/subunit of cytochrome bc1 complex (Ubiquinol-cytochrome c reductase) [ 81648]
Families:   a domain/subunit of cytochrome bc1 complex (Ubiquinol-cytochrome c reductase) [ 81647] (2)


Superfamily statistics
Genomes (1,224) Uniprot 2018_03 genome PDB chains (SCOP 1.75)
Domains 1,591 149,954 8
Proteins 1,540 149,479 8


Functional annotation
General category Metabolism
Detailed category Energy

Document:
Function annotation of SCOP domain superfamilies

InterPro annotation
Cross references IPR005798 SSF81648 Protein matches
Abstract

In the mitochondrion of eukaryotes and in aerobic prokaryotes, cytochrome b is a component of respiratory chain complex III - also known as the bc1 complex or ubiquinol-cytochrome c reductase. In plant chloroplasts and cyanobacteria, there is a analogous protein, cytochrome b6, a component of the plastoquinone-plastocyanin reductase , also known as the b6f complex.

Cytochrome b/b6 [PubMed2509716, PubMed8329437] is an integral membrane protein of approximately 400 amino acid residues that probably has 8 transmembrane segments. In plants and cyanobacteria, cytochrome b6 consists of two subunits encoded by the petB and petD genes. The sequence of petB is colinear with the N-terminal part of mitochondrial cytochrome b, while petD corresponds to the C-terminal part. Cytochrome b/b6 non-covalently binds two heme groups, known as b562 and b566. Four conserved histidine residues are postulated to be the ligands of the iron atoms of these two heme groups.

Apart from regions around some of the histidine heme ligands, there are a few conserved regions in the sequence of b/b6. The best conserved of these regions includes an invariant P-E-W triplet which lies in the loop that separates the fifth and sixth transmembrane segments. It seems to be important for electron transfer at the ubiquinone redox site - called Qz or Qo (where o stands for outside) - located on the outer side of the membrane. This entry is the C-terminus of these proteins.


InterPro database


PDBeMotif information about ligands, sequence and structure motifs
Cross references PDB entries
Ligand binding statistics
Nucleic-acid binding statistics
Occurrence of secondary structure elements
Occurrence of small 3D structural motifs

PDBeMotif resource

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Internal database links

Browse genome assignments for this superfamily. The SUPERFAMILY hidden Markov model library has been used to carry out SCOP domain assignments to all genomes at the superfamily level.


Alignments of sequences to 5 models in this superfamily are available by clicking on the 'Alignments' icon above. PDB sequences less than 40% identical are shown by default, but any other sequence(s) may be aligned. Select PDB sequences, genome sequences, or paste in or upload your own sequences.


Browse and view proteins in genomes which have different domain combinations including a a domain/subunit of cytochrome bc1 complex (Ubiquinol-cytochrome c reductase) domain.


Examine the distribution of domain superfamilies, or families, across the major taxonomic kingdoms or genomes within a kingdom. This gives an immediate impression of how superfamilies, or families, are restricted to certain kingdoms of life.


Explore domain occurrence network where nodes represent genomes and edges are domain architectures (shared between genomes) containing the superfamily of interest.

There are 5 hidden Markov models representing the a domain/subunit of cytochrome bc1 complex (Ubiquinol-cytochrome c reductase) superfamily. Information on how the models are built, and plots showing hydrophobicity, match emmission probabilities and insertion/deletion probabilities can be inspected.


Jump to [ Top of page · SCOP classification · InterPro annotation · PDBeMotif links · Functional annotation · Internal database links ]