UniProtKB - P00163 (CYB_YEAST)
Cytochrome b
COB
Functioni
Component of the ubiquinol-cytochrome c oxidoreductase, a multisubunit transmembrane complex that is part of the mitochondrial electron transport chain which drives oxidative phosphorylation. The respiratory chain contains 3 multisubunit complexes succinate dehydrogenase (complex II, CII), ubiquinol-cytochrome c oxidoreductase (cytochrome b-c1 complex, complex III, CIII) and cytochrome c oxidase (complex IV, CIV), that cooperate to transfer electrons derived from NADH and succinate to molecular oxygen, creating an electrochemical gradient over the inner membrane that drives transmembrane transport and the ATP synthase. The cytochrome b-c1 complex catalyzes electron transfer from ubiquinol to cytochrome c, linking this redox reaction to translocation of protons across the mitochondrial inner membrane, with protons being carried across the membrane as hydrogens on the quinol. In the process called Q cycle, 2 protons are consumed from the matrix, 4 protons are released into the intermembrane space and 2 electrons are passed to cytochrome c (Probable). Cytochrome b is a catalytic core subunit containing 2 b-type hemes BL and BH topographically segregated in the quinone reduction (Qi) and quinol oxidation (Q0) sites on opposite sides of the membrane (PubMed:18390544).
3 Publications1 PublicationMiscellaneous
Catalytic activityi
- a quinol + 2 Fe(III)-[cytochrome c](out) = a quinone + 2 Fe(II)-[cytochrome c](out) + 2 H+(out)2 PublicationsEC:7.1.1.82 Publications
Cofactori
Sites
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Binding sitei | 16 | Ubiquinone1 Publication | 1 | |
Metal bindingi | 82 | Iron 1 (heme b562 axial ligand); via tele nitrogenCombined sources4 Publications | 1 | |
Metal bindingi | 96 | Iron 2 (heme b566 axial ligand); via tele nitrogenCombined sources4 Publications | 1 | |
Metal bindingi | 183 | Iron 1 (heme b562 axial ligand); via tele nitrogenCombined sources4 Publications | 1 | |
Metal bindingi | 197 | Iron 2 (heme b566 axial ligand); via tele nitrogenCombined sources4 Publications | 1 | |
Binding sitei | 202 | UbiquinoneBy similarity | 1 |
GO - Molecular functioni
- metal ion binding Source: UniProtKB-KW
- ubiquinol-cytochrome-c reductase activity Source: UniProtKB
GO - Biological processi
- aerobic respiration Source: SGD
- cellular respiration Source: ComplexPortal
- mitochondrial electron transport, ubiquinol to cytochrome c Source: UniProtKB
Keywordsi
Molecular function | Translocase |
Biological process | Electron transport, Respiratory chain, Transport |
Ligand | Heme, Iron, Metal-binding, Ubiquinone |
Enzyme and pathway databases
Reactomei | R-SCE-611105, Respiratory electron transport |
Protein family/group databases
TCDBi | 3.D.3.3.1, the proton-translocating quinol:cytochrome c reductase (qcr) superfamily |
Names & Taxonomyi
Protein namesi | Recommended name: Cytochrome b (EC:7.1.1.82 Publications)Alternative name(s): Complex III subunit 3 Complex III subunit CYTB Complex III subunit III Cytochrome b-c1 complex subunit 3 Cytochrome b-c1 complex subunit CYTB Ubiquinol-cytochrome c oxidoreductase complex cytochrome b subunit |
Gene namesi | Name:COB Synonyms:CYTB Ordered Locus Names:Q0105 |
Encoded oni | Mitochondrion |
Organismi | Saccharomyces cerevisiae (strain ATCC 204508 / S288c) (Baker's yeast) |
Taxonomic identifieri | 559292 [NCBI] |
Taxonomic lineagei | Eukaryota › Fungi › Dikarya › Ascomycota › Saccharomycotina › Saccharomycetes › Saccharomycetales › Saccharomycetaceae › Saccharomyces › |
Proteomesi |
|
Organism-specific databases
SGDi | S000007270, COB |
VEuPathDBi | FungiDB:Q0105 |
Subcellular locationi
Mitochondrion
- Mitochondrion inner membrane 3 Publications; Multi-pass membrane protein 5 Publications
Mitochondrion
- integral component of mitochondrial inner membrane Source: UniProtKB
- mitochondrial inner membrane Source: ComplexPortal
- mitochondrial respiratory chain complex III Source: UniProtKB
- mitochondrion Source: SGD
Topology
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Topological domaini | 1 – 27 | Mitochondrial matrix1 Publication2 PublicationsAdd BLAST | 27 | |
Transmembranei | 28 – 51 | HelicalCombined sources4 PublicationsAdd BLAST | 24 | |
Topological domaini | 52 – 74 | Mitochondrial intermembrane1 Publication2 PublicationsAdd BLAST | 23 | |
Transmembranei | 75 – 102 | HelicalCombined sources4 PublicationsAdd BLAST | 28 | |
Topological domaini | 103 – 110 | Mitochondrial matrix1 Publication2 Publications | 8 | |
Transmembranei | 111 – 135 | HelicalCombined sources4 PublicationsAdd BLAST | 25 | |
Topological domaini | 136 – 172 | Mitochondrial intermembrane1 Publication2 PublicationsAdd BLAST | 37 | |
Transmembranei | 173 – 204 | HelicalCombined sources4 PublicationsAdd BLAST | 32 | |
Topological domaini | 205 – 223 | Mitochondrial matrix1 Publication2 PublicationsAdd BLAST | 19 | |
Transmembranei | 224 – 246 | HelicalCombined sources4 PublicationsAdd BLAST | 23 | |
Topological domaini | 247 – 287 | Mitochondrial intermembrane1 Publication2 PublicationsAdd BLAST | 41 | |
Transmembranei | 288 – 308 | HelicalCombined sources4 PublicationsAdd BLAST | 21 | |
Topological domaini | 309 – 319 | Mitochondrial matrix1 Publication2 PublicationsAdd BLAST | 11 | |
Transmembranei | 320 – 340 | HelicalCombined sources4 PublicationsAdd BLAST | 21 | |
Topological domaini | 341 – 347 | Mitochondrial intermembrane1 Publication2 Publications | 7 | |
Transmembranei | 348 – 364 | HelicalCombined sources4 PublicationsAdd BLAST | 17 | |
Topological domaini | 365 – 385 | Mitochondrial matrix1 Publication2 PublicationsAdd BLAST | 21 |
Keywords - Cellular componenti
Membrane, Mitochondrion, Mitochondrion inner membranePTM / Processingi
Molecule processing
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
ChainiPRO_0000061769 | 1 – 385 | Cytochrome bAdd BLAST | 385 |
Proteomic databases
PaxDbi | P00163 |
TopDownProteomicsi | P00163 |
Interactioni
Subunit structurei
Component of the ubiquinol-cytochrome c oxidoreductase (cytochrome b-c1 complex, complex III, CIII), a multisubunit enzyme composed of 10 subunits. The complex is composed of 3 respiratory subunits cytochrome b (COB), cytochrome c1 (CYT1) and Rieske protein (RIP1), 2 core protein subunits COR1 and QCR2, and 5 low-molecular weight protein subunits QCR6, QCR7, QCR8, QCR9 and QCR10 (PubMed:10873857, PubMed:11880631, PubMed:8031140, PubMed:30598554). The complex exists as an obligatory dimer and forms supercomplexes (SCs) in the inner mitochondrial membrane with a monomer or a dimer of cytochrome c oxidase (complex IV, CIV), resulting in 2 different assemblies (supercomplexes III2IV and III2IV2) (PubMed:10775262, PubMed:10764779, PubMed:30598556, PubMed:30598554).
7 PublicationsProtein-protein interaction databases
BioGRIDi | 34779, 37 interactors |
ComplexPortali | CPX-567, Mitochondrial respiratory chain complex III |
IntActi | P00163, 4 interactors |
STRINGi | 4932.Q0105 |
Miscellaneous databases
RNActi | P00163, protein |
Structurei
Secondary structure
3D structure databases
AlphaFoldDBi | P00163 |
SMRi | P00163 |
ModBasei | Search... |
PDBe-KBi | Search... |
Miscellaneous databases
EvolutionaryTracei | P00163 |
Family & Domainsi
Sequence similaritiesi
Keywords - Domaini
Transmembrane, Transmembrane helixPhylogenomic databases
eggNOGi | KOG4663, Eukaryota |
GeneTreei | ENSGT00390000017948 |
HOGENOMi | CLU_031114_3_0_1 |
InParanoidi | P00163 |
OMAi | RFFAFHF |
Family and domain databases
CDDi | cd00290, cytochrome_b_C, 1 hit cd00284, Cytochrome_b_N, 1 hit |
Gene3Di | 1.20.810.10, 1 hit |
InterProi | View protein in InterPro IPR005798, Cyt_b/b6_C IPR036150, Cyt_b/b6_C_sf IPR005797, Cyt_b/b6_N IPR027387, Cytb/b6-like_sf IPR030689, Cytochrome_b IPR016174, Di-haem_cyt_TM |
Pfami | View protein in Pfam PF00032, Cytochrom_B_C, 1 hit PF00033, Cytochrome_B, 1 hit |
PIRSFi | PIRSF038885, COB, 1 hit |
SUPFAMi | SSF81342, SSF81342, 1 hit SSF81648, SSF81648, 1 hit |
PROSITEi | View protein in PROSITE PS51003, CYTB_CTER, 1 hit PS51002, CYTB_NTER, 1 hit |
i Sequence
Sequence statusi: Complete.
10 20 30 40 50
MAFRKSNVYL SLVNSYIIDS PQPSSINYWW NMGSLLGLCL VIQIVTGIFM
60 70 80 90 100
AMHYSSNIEL AFSSVEHIMR DVHNGYILRY LHANGASFFF MVMFMHMAKG
110 120 130 140 150
LYYGSYRSPR VTLWNVGVII FILTIATAFL GYCCVYGQMS HWGATVITNL
160 170 180 190 200
FSAIPFVGND IVSWLWGGFS VSNPTIQRFF ALHYLVPFII AAMVIMHLMA
210 220 230 240 250
LHIHGSSNPL GITGNLDRIP MHSYFIFKDL VTVFLFMLIL ALFVFYSPNT
260 270 280 290 300
LGHPDNYIPG NPLVTPASIV PEWYLLPFYA ILRSIPDKLL GVITMFAAIL
310 320 330 340 350
VLLVLPFTDR SVVRGNTFKV LSKFFFFIFV FNFVLLGQIG ACHVEVPYVL
360 370 380
MGQIATFIYF AYFLIIVPVI STIENVLFYI GRVNK
Experimental Info
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Sequence conflicti | 122 | I → T in CAA58861 (PubMed:7737175).Curated | 1 | |
Sequence conflicti | 122 | I → T in AAA32151 (PubMed:7004642).Curated | 1 | |
Sequence conflicti | 269 | I → ID in CAA24073 (PubMed:6253454).Curated | 1 | |
Sequence conflicti | 269 | I → ID no nucleotide entry (PubMed:6383504).Curated | 1 |
Natural variant
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Natural varianti | 131 | G → S in mutant W7 which is respiratory deficient. | 1 |
Sequence databases
Select the link destinations: EMBLi GenBanki DDBJi Links Updated | V00696 Genomic DNA Translation: CAA24073.2 Sequence problems. X84042 mRNA Translation: CAA58861.1 KP263414 Genomic DNA Translation: AIZ98890.1 J01473, J01472 Genomic DNA Translation: AAA32151.2 J01475, J01474 Genomic DNA Translation: AAA32152.2 |
PIRi | A00159, CBBY S78660 |
RefSeqi | NP_009315.1, NC_001224.1 |
Genome annotation databases
EnsemblFungii | Q0105_mRNA; Q0105; Q0105 |
GeneIDi | 854583 |
KEGGi | sce:Q0105 |
Similar proteinsi
Cross-referencesi
Sequence databases
Select the link destinations: EMBLi GenBanki DDBJi Links Updated | V00696 Genomic DNA Translation: CAA24073.2 Sequence problems. X84042 mRNA Translation: CAA58861.1 KP263414 Genomic DNA Translation: AIZ98890.1 J01473, J01472 Genomic DNA Translation: AAA32151.2 J01475, J01474 Genomic DNA Translation: AAA32152.2 |
PIRi | A00159, CBBY S78660 |
RefSeqi | NP_009315.1, NC_001224.1 |
3D structure databases
Select the link destinations: PDBei RCSB PDBi PDBji Links Updated | PDB entry | Method | Resolution (Å) | Chain | Positions | PDBsum |
1EZV | X-ray | 2.30 | C | 1-385 | [»] | |
1KB9 | X-ray | 2.30 | C | 1-385 | [»] | |
1KYO | X-ray | 2.97 | C/N | 1-385 | [»] | |
1P84 | X-ray | 2.50 | C | 1-385 | [»] | |
2IBZ | X-ray | 2.30 | C | 1-385 | [»] | |
3CX5 | X-ray | 1.90 | C/N | 1-385 | [»] | |
3CXH | X-ray | 2.50 | C/N | 1-385 | [»] | |
4PD4 | X-ray | 3.04 | C | 1-385 | [»] | |
6GIQ | electron microscopy | 3.23 | C/N | 1-385 | [»] | |
6HU9 | electron microscopy | 3.35 | C/N | 1-385 | [»] | |
6T0B | electron microscopy | 2.80 | C/N | 1-385 | [»] | |
6T15 | electron microscopy | 3.29 | C/N | 1-385 | [»] | |
6YMX | electron microscopy | 3.17 | C/N | 1-385 | [»] | |
AlphaFoldDBi | P00163 | |||||
SMRi | P00163 | |||||
ModBasei | Search... | |||||
PDBe-KBi | Search... |
Protein-protein interaction databases
BioGRIDi | 34779, 37 interactors |
ComplexPortali | CPX-567, Mitochondrial respiratory chain complex III |
IntActi | P00163, 4 interactors |
STRINGi | 4932.Q0105 |
Chemistry databases
ChEMBLi | CHEMBL4296317 |
Protein family/group databases
TCDBi | 3.D.3.3.1, the proton-translocating quinol:cytochrome c reductase (qcr) superfamily |
Proteomic databases
PaxDbi | P00163 |
TopDownProteomicsi | P00163 |
Genome annotation databases
EnsemblFungii | Q0105_mRNA; Q0105; Q0105 |
GeneIDi | 854583 |
KEGGi | sce:Q0105 |
Organism-specific databases
SGDi | S000007270, COB |
VEuPathDBi | FungiDB:Q0105 |
Phylogenomic databases
eggNOGi | KOG4663, Eukaryota |
GeneTreei | ENSGT00390000017948 |
HOGENOMi | CLU_031114_3_0_1 |
InParanoidi | P00163 |
OMAi | RFFAFHF |
Enzyme and pathway databases
Reactomei | R-SCE-611105, Respiratory electron transport |
Miscellaneous databases
EvolutionaryTracei | P00163 |
PROi | PR:P00163 |
RNActi | P00163, protein |
Family and domain databases
CDDi | cd00290, cytochrome_b_C, 1 hit cd00284, Cytochrome_b_N, 1 hit |
Gene3Di | 1.20.810.10, 1 hit |
InterProi | View protein in InterPro IPR005798, Cyt_b/b6_C IPR036150, Cyt_b/b6_C_sf IPR005797, Cyt_b/b6_N IPR027387, Cytb/b6-like_sf IPR030689, Cytochrome_b IPR016174, Di-haem_cyt_TM |
Pfami | View protein in Pfam PF00032, Cytochrom_B_C, 1 hit PF00033, Cytochrome_B, 1 hit |
PIRSFi | PIRSF038885, COB, 1 hit |
SUPFAMi | SSF81342, SSF81342, 1 hit SSF81648, SSF81648, 1 hit |
PROSITEi | View protein in PROSITE PS51003, CYTB_CTER, 1 hit PS51002, CYTB_NTER, 1 hit |
MobiDBi | Search... |
Entry informationi
Entry namei | CYB_YEAST | |
Accessioni | P00163Primary (citable) accession number: P00163 Secondary accession number(s): A0A0A7NYK0 Q9ZZW9 | |
Entry historyi | Integrated into UniProtKB/Swiss-Prot: | July 21, 1986 |
Last sequence update: | April 23, 2003 | |
Last modified: | May 25, 2022 | |
This is version 187 of the entry and version 3 of the sequence. See complete history. | ||
Entry statusi | Reviewed (UniProtKB/Swiss-Prot) | |
Annotation program | Fungal Protein Annotation Program |
Miscellaneousi
Keywords - Technical termi
3D-structure, Direct protein sequencing, Reference proteomeDocuments
- Yeast
Yeast (Saccharomyces cerevisiae): entries, gene names and cross-references to SGD - PDB cross-references
Index of Protein Data Bank (PDB) cross-references - SIMILARITY comments
Index of protein domains and families