QCR8/YJL166W Summary Help

Standard Name QCR8 1
Systematic Name YJL166W
Alias COR5
Feature Type ORF, Verified
Description Subunit 8 of ubiquinol cytochrome-c reductase (Complex III); Complex III is a component of the mitochondrial inner membrane electron transport chain; oriented facing the intermembrane space; expression is regulated by Abf1p and Cpf1p (1, 2, 3 and see Summary Paragraph)
Name Description ubiQuinol-cytochrome C oxidoReductase 1
Chromosomal Location
ChrX:106434 to 106718 | ORF Map | GBrowse
Gene Ontology Annotations All QCR8 GO evidence and references
  View Computational GO annotations for QCR8
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 5 genes
Classical genetics
Large-scale survey
222 total interaction(s) for 211 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 6
  • Affinity Capture-RNA: 3
  • Affinity Capture-Western: 9
  • Biochemical Activity: 1
  • Co-fractionation: 1
  • PCA: 1

Genetic Interactions
  • Dosage Lethality: 2
  • Negative Genetic: 160
  • Positive Genetic: 38
  • Synthetic Lethality: 1

Expression Summary
Length (a.a.) 94
Molecular Weight (Da) 10,975
Isoelectric Point (pI) 10.57
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrX:106434 to 106718 | ORF Map | GBrowse
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..285 106434..106718 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000003702

The cytochrome bc1 complex (also known as ubiquinol:cytochrome c oxidoreductase, ubiquinol:ferricytochrome c oxidoreductase, and respiratory complex III) is a highly conserved enzyme of the mitochondrial respiratory chain (reviewed in 4). In S. cerevisiae it consists of three catalytic subunits, Cobp, Rip1p, and Cyt1p, plus seven additional subunits: Cor1p, Qcr2p, Qcr6p, Qcr7p, Qcr8p, Qcr9p, and Qcr10p (4, 5). The crystal structure of the complex shows that two functional units, each containing these ten subunits, associate with each other in the mitochondrial inner membrane (6). Assembly of a functional complex requires two proteins, Cbp3p and Cbp4p, that are not components of the complex but may associate with it during assembly (7). It also requires Bcs1p, an AAA-family ATPase that interacts with a precursor of the complex to mediate incorporation of the Rip1p and Qcr10p subunits (8). The mechanism of energy transfer by the complex, known as the protonmotive Q cycle, has been studied in detail (reviewed in 4). The net result of the Q cycle is the stepwise transfer of an electron through the complex from ubiquinol to cytochrome c (Cyc1p), coupled with the translocation of a proton across the mitochondrial inner membrane (4). The function of the cytochrome bc1 complex is essential to the energy-generating process of oxidative phosphorylation, which is carried out by the enzyme complexes of the mitochondrial respiratory chain.

The Qcr8p subunit is essential to activity of the cytochrome bc1 complex: the qcr8 complete deletion, and certain missense mutations, completely block respiratory growth (9). Substitution of a proline residue with a positively charged amino acid in the single transmembrane helix of Qcr8p, which constitutes part of the ubiquinone binding site, causes instability and reduced function of the complex and partial loss of cytochrome b (Cobp) (9). Certain qcr8 mutations affect the activity of the succinate-ubiquinone reductase complex (complex II), suggesting that Qcr8p may mediate an interaction between these two mitochondrial respiratory chain complexes (10). Qcr8p is conserved across eukaryotes (3, 11, 12), and its bovine counterpart can partially substitute for the function of yeast Qcr8p (13).

Last updated: 2007-07-26 Contact SGD

References cited on this page View Complete Literature Guide for QCR8
1) de Winde JH and Grivell LA  (1992) Global regulation of mitochondrial biogenesis in Saccharomyces cerevisiae: ABF1 and CPF1 play opposite roles in regulating expression of the QCR8 gene, which encodes subunit VIII of the mitochondrial ubiquinol-cytochrome c oxidoreductase. Mol Cell Biol 12(6):2872-83
2) Hemrika W and Berden JA  (1990) Membrane topography of the subunits of ubiquinol-cytochrome-c oxidoreductase of Saccharomyces cerevisiae. The 14-kDa and the 11-kDa subunits face opposite sides of the mitochondrial inner membrane. Eur J Biochem 192(3):761-5
3) Maarse AC and Grivell LA  (1987) Nucleotide sequence of the gene encoding the 11-kDa subunit of the ubiquinol-cytochrome-c oxidoreductase in Saccharomyces cerevisiae. Eur J Biochem 165(2):419-25
4) Hunte C, et al.  (2003) Protonmotive pathways and mechanisms in the cytochrome bc1 complex. FEBS Lett 545(1):39-46
5) Brandt U, et al.  (1994) Isolation and characterization of QCR10, the nuclear gene encoding the 8.5-kDa subunit 10 of the Saccharomyces cerevisiae cytochrome bc1 complex. J Biol Chem 269(17):12947-53
6) Hunte C, et al.  (2000) Structure at 2.3 A resolution of the cytochrome bc(1) complex from the yeast Saccharomyces cerevisiae co-crystallized with an antibody Fv fragment. Structure 8(6):669-84
7) Kronekova Z and Rodel G  (2005) Organization of assembly factors Cbp3p and Cbp4p and their effect on bc(1) complex assembly in Saccharomyces cerevisiae. Curr Genet 47(4):203-12
8) Cruciat CM, et al.  (1999) Bcs1p, an AAA-family member, is a chaperone for the assembly of the cytochrome bc(1) complex. EMBO J 18(19):5226-33
9) Hagerman RA, et al.  (2006) Ubiquinone accumulates in the mitochondria of yeast mutated in the ubiquinone binding protein, Qcr8p. Biochem Biophys Res Commun 344(1):241-5
10) Bruel C, et al.  (1996) Subunit 8 of the Saccharomyces cerevisiae cytochrome bc1 complex interacts with succinate-ubiquinone reductase complex. J Bioenerg Biomembr 28(1):59-68
11) Boumans H, et al.  (1995) cDNA sequence of subunit VIII of ubiquinol-cytochrome-c oxidoreductase from Schizosaccharomyces pombe. Biochim Biophys Acta 1229(3):386-8
12) Boumans H, et al.  (1995) Identification of additional homologues of subunits VII and VIII of the ubiquinol-cytochrome c oxidoreductase enables definition of consensus sequences. FEBS Lett 368(1):105-9
13) Boumans H, et al.  (1997) The role of subunit VIII in the structural stability of the bc1 complex from Saccharomyces cerevisiae studied using hybrid complexes. Eur J Biochem 249(3):762-9