CYT1/YOR065W Summary Help

Standard Name CYT1
Systematic Name YOR065W
Alias CTC1 , YOR29-16
Feature Type ORF, Verified
Description Cytochrome c1; component of the mitochondrial respiratory chain; expression is regulated by the heme-activated, glucose-repressed Hap2p/3p/4p/5p CCAAT-binding complex (1, 2, 3 and see Summary Paragraph)
Gene Product Alias cytochrome c1 3
Chromosomal Location
ChrXV:447439 to 448368 | ORF Map | GBrowse
Gene Ontology Annotations All CYT1 GO evidence and references
  View Computational GO annotations for CYT1
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Regulators 7 genes
Classical genetics
Large-scale survey
251 total interaction(s) for 177 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 10
  • Affinity Capture-RNA: 2
  • Affinity Capture-Western: 12
  • Co-crystal Structure: 1
  • Co-localization: 2
  • PCA: 1
  • Reconstituted Complex: 2

Genetic Interactions
  • Dosage Rescue: 1
  • Negative Genetic: 184
  • Phenotypic Enhancement: 1
  • Phenotypic Suppression: 4
  • Positive Genetic: 17
  • Synthetic Growth Defect: 7
  • Synthetic Lethality: 2
  • Synthetic Rescue: 5

Expression Summary
Length (a.a.) 309
Molecular Weight (Da) 34,054
Isoelectric Point (pI) 8.2
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXV:447439 to 448368 | ORF Map | GBrowse
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..930 447439..448368 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 SGDIDS000005591

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.

Cyt1p, more commonly known as cytochrome c1, is one of the catalytic subunits of the cytochrome bc1 complex and is essential for electron transfer within the complex and for respiratory growth (9, 4). Maturation and mitochondrial import of Cyt1p involve proteolytic cleavages of the N- and C-terminal regions as well as insertion of a heme prosthetic group, which is mediated by cyctochrome c1 heme lyase (Cyt2p) (10, 11, 12). CYT1 is conserved across both prokaryotes and eukaryotes (13); its human homolog is CYC1 (OMIM; note that the S. cerevisiae gene named CYC1 encodes a distinct protein, cytochrome c).

Last updated: 2007-07-26 Contact SGD

References cited on this page View Complete Literature Guide for CYT1
1) Schneider JC and Guarente L  (1991) Regulation of the yeast CYT1 gene encoding cytochrome c1 by HAP1 and HAP2/3/4. Mol Cell Biol 11(10):4934-42
2) Boumans H, et al.  (1998) The respiratory chain in yeast behaves as a single functional unit. J Biol Chem 273(9):4872-7
3) Sadler I, et al.  (1984) Sequencing of the nuclear gene for the yeast cytochrome c1 precursor reveals an unusually complex amino-terminal presequence. EMBO J 3(9):2137-43
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) Crivellone MD, et al.  (1988) Assembly of the mitochondrial membrane system. Analysis of structural mutants of the yeast coenzyme QH2-cytochrome c reductase complex. J Biol Chem 263(28):14323-33
10) Zollner A, et al.  (1992) Molecular cloning and characterization of the Saccharomyces cerevisiae CYT2 gene encoding cytochrome-c1-heme lyase. Eur J Biochem 207(3):1093-100
11) Arnold I, et al.  (1998) Two distinct and independent mitochondrial targeting signals function in the sorting of an inner membrane protein, cytochrome c1. J Biol Chem 273(3):1469-76
12) Gasser SM, et al.  (1982) Imported mitochondrial proteins cytochrome b2 and cytochrome c1 are processed in two steps. Proc Natl Acad Sci U S A 79(2):267-71
13) Trumpower BL  (1990) Cytochrome bc1 complexes of microorganisms. Microbiol Rev 54(2):101-29