QCR7/YDR529C Summary Help

Standard Name QCR7 1
Systematic Name YDR529C
Alias COR4 , CRO1 , UCR7
Feature Type ORF, Verified
Description Subunit 7 of ubiquinol cytochrome-c reductase (Complex III); Complex III is a component of the mitochondrial inner membrane electron transport chain; oriented facing the mitochondrial matrix; N-terminus appears to play a role in complex assembly (2, 3, 4 and see Summary Paragraph)
Name Description ubiQuinol-cytochrome C oxidoReductase 1
Chromosomal Location
ChrIV:1496548 to 1496165 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Gene Ontology Annotations All QCR7 GO evidence and references
  View Computational GO annotations for QCR7
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 4 genes
Classical genetics
Large-scale survey
59 total interaction(s) for 58 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 4
  • Affinity Capture-RNA: 5
  • Affinity Capture-Western: 1
  • Co-fractionation: 1
  • PCA: 1
  • Two-hybrid: 1

Genetic Interactions
  • Negative Genetic: 33
  • Positive Genetic: 10
  • Synthetic Growth Defect: 2
  • Synthetic Rescue: 1

Expression Summary
Length (a.a.) 127
Molecular Weight (Da) 14,565
Isoelectric Point (pI) 5.76
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrIV:1496548 to 1496165 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..384 1496548..1496165 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 SGDIDS000002937

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 5). 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 (5, 6). 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 (7). 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 (8). 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 (9). The mechanism of energy transfer by the complex, known as the protonmotive Q cycle, has been studied in detail (reviewed in 5). 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 (5). 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.

Qcr7p, known as the ubiquinone-binding subunit, is essential for assembly and activity of the cytochrome bc1 complex (10). Qcr7p, Cor1p, and Qcr2p comprise a large domain of the complex that extends into the mitochondrial matrix (5). Qcr7p may be involved in electron transport through the region of the complex known as center o (11), and genetic evidence also suggests a role in proton uptake by the complex (12). Unlike most mitochondrially imported proteins, Qcr7p does not have an N-terminal cleavable presequence that directs import; however, mutations in the N-terminal region cause instability of the cytochrome bc1 complex, and levels of Rip1p and Qcr8p are decreased, indicating that they are not fully assembled into the complex (4, 13). QCR7 is conserved across eukaryotes (14), although the potato and human orthologs fail to functionally complement the qcr7 null mutation (15).

Last updated: 2007-07-26 Contact SGD

References cited on this page View Complete Literature Guide for QCR7
1) Mulder W, et al.  (1994) Isolation and characterisation of the linked genes APA2 and QCR7, coding for Ap4A phosphorylase II and the 14 kDa subunit VII of the mitochondrial bc1-complex in the yeast Kluyveromyces lactis. Biochim Biophys Acta 1219(3):719-23
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) De Haan M, et al.  (1984) The biosynthesis of the ubiquinol-cytochrome c reductase complex in yeast. DNA sequence analysis of the nuclear gene coding for the 14-kDa subunit. Eur J Biochem 138(1):169-77
4) Lee SY, et al.  (2001) The N-terminus of the Qcr7 protein of the cytochrome bc(1) complex in S. cerevisiae may be involved in facilitating stability of the subcomplex with the Qcr8 protein and cytochrome b. Arch Biochem Biophys 393(2):215-21
5) Hunte C, et al.  (2003) Protonmotive pathways and mechanisms in the cytochrome bc1 complex. FEBS Lett 545(1):39-46
6) 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
7) 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
8) 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
9) 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
10) Schoppink PJ, et al.  (1989) Inactivation of the gene encoding the 14-kDa subunit VII of yeast ubiquinol. Cytochrome c oxidoreductase and analysis of the resulting mutant. Eur J Biochem 181(2):475-83
11) Japa S, et al.  (1987) Subunit VII, the ubiquinone-binding protein, of the cytochrome b-c1 complex of yeast mitochondria is involved in electron transport at center o and faces the matrix side of the membrane. J Biol Chem 262(12):5441-4
12) Lee SY, et al.  (2001) The functional role of conserved acidic residues of the Qcr7 protein of the cytochrome bc(1) complex in Saccharomyces cerevisiae. Arch Biochem Biophys 393(2):207-14
13) Malaney S, et al.  (1997) The N terminus of the Qcr7 protein of the cytochrome bc1 complex is not essential for import into mitochondria in Saccharomyces cerevisiae but is essential for assembly of the complex. J Biol Chem 272(28):17495-501
14) 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
15) van Wilpe S, et al.  (1999) Functional complementation analysis of yeast bc1 mutants. A study of the mitochondrial import of heterologous and hybrid proteins. Eur J Biochem 264(3):825-32