Cytochrome c oxidase subunit 5B, mitochondrial (COX5B)
The protein contains 129 amino acids for an estimated molecular weight of 13696 Da.
Component of the cytochrome c oxidase, the last enzyme in 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. Cytochrome c oxidase is the component of the respiratory chain that catalyzes the reduction of oxygen to water. Electrons originating from reduced cytochrome c in the intermembrane space (IMS) are transferred via the dinuclear copper A center (CU(A)) of subunit 2 and heme A of subunit 1 to the active site in subunit 1, a binuclear center (BNC) formed by heme A3 and copper B (CU(B)). The BNC reduces molecular oxygen to 2 water molecules using 4 electrons from cytochrome c in the IMS and 4 protons from the mitochondrial matrix. (updated: Feb. 26, 2020)
Protein identification was indicated in the following studies:
- Lange and co-workers. (2014) Annotating N termini for the human proteome project: N termini and Nα-acetylation status differentiate stable cleaved protein species from degradation remnants in the human erythrocyte proteome. J Proteome Res. 13(4), 2028-2044.
- Wilson and co-workers. (2016) Comparison of the Proteome of Adult and Cord Erythroid Cells, and Changes in the Proteome Following Reticulocyte Maturation. Mol Cell Proteomics. 15(6), 1938-1946.
- Bryk and co-workers. (2017) Quantitative Analysis of Human Red Blood Cell Proteome. J Proteome Res. 16(8), 2752-2761.
- Chu and co-workers. (2018) Quantitative mass spectrometry of human reticulocytes reveal proteome-wide modifications during maturation. Br J Haematol. 180(1), 118-133.
Methods
The following articles were analysed to gather the proteome content of erythrocytes.
The gene or protein list provided in the studies were processed using the ID mapping API of Uniprot in September 2018. The number of proteins identified and mapped without ambiguity in these studies is indicated below.
Only Swiss-Prot entries (reviewed) were considered for protein evidence assignation.
| Publication | Identification 1 | Uniprot mapping 2 | Not mapped / Obsolete | TrEMBL | Swiss-Prot |
|---|---|---|---|---|---|
| Goodman (2013) | 2289 (gene list) | 2278 | 53 | 20599 | 2269 |
| Lange (2014) | 1234 | 1234 | 7 | 28 | 1224 |
| Hegedus (2015) | 2638 | 2622 | 0 | 235 | 2387 |
| Wilson (2016) | 1658 | 1528 | 170 | 291 | 1068 |
| d'Alessandro (2017) | 1826 | 1817 | 2 | 0 | 1815 |
| Bryk (2017) | 2090 | 2060 | 10 | 108 | 1942 |
| Chu (2018) | 1853 | 1804 | 55 | 362 | 1387 |
1 as available in the article and/or in supplementary material
2 uniprot mapping returns all protein isoforms as one entry
The compilation of older studies can be retrieved from the Red Blood Cell Collection database.
The data and differentiation stages presented below come from the proteomic study and analysis performed by our partners of the GReX consortium, more details are available in their published work.
(right-click above to access to more options from the contextual menu)
Biological Process
Mitochondrial ATP synthesis coupled proton transport
Mitochondrial electron transport, cytochrome c to oxygen
Respiratory gaseous exchange by respiratory system
Cellular Component
Mitochondrial inner membrane
Mitochondrial respiratory chain complex IV
Mitochondrion
The reference OMIM entry for this protein is 123866
Cytochrome c oxidase, subunit vb; cox5b
DESCRIPTION
Subunit Vb of mammalian cytochrome c oxidase (COX; EC 1.9.3.1) is encoded by a nuclear gene and assembled with the other 12 COX subunits encoded in both mitochondrial and nuclear DNA. COX, the terminal enzyme of the electron transport chain, transfers electrons from reduced cytochrome c to oxygen and, in the process, generates an electrochemical gradient across the mitochondrial inner membrane. The enzyme is composed of 13 polypeptide subunits, 3 of which are encoded in mitochondrial DNA and 10 in nuclear DNA. The nuclear-coded COX subunits can be divided into 2 groups: those with muscle-specific isoforms and those that are identical in all tissues, such as COX5B (summary by Lomax et al., 1991).CLONING
Lomax et al. (1991) reported the isolation and DNA sequence of the expressed gene for human COX subunit Vb and the chromosomal location of the expressed gene and 7 pseudogenes as determined by analysis of panels of somatic cell hybrids with cDNA, genomic, and intron probes.GENE STRUCTURE
Lomax et al. (1991) determined that the COX5B gene contains 5 exons and 4 introns. The 4 coding exons span a region of approximately 2.4 kb. The 5-prime end of the COX5B gene is GC-rich and contains many HpaII sites.MAPPING
Using genomic Southern blot analysis of human DNA probed with the human COX Vb cDNA, Lomax et al. (1991) identified 8 restriction fragments containing COX Vb-related sequences that were mapped to different chromosomes with panels of human/Chinese somatic cell hybrids. Because only 1 of these fragments hybridized with a 210-bp probe from intron 4, Lomax et al. (1991) concluded that there is a single expressed gene in the human genome, which they mapped to 2cen-q13. ... More on the omim web site
March 3, 2020: Protein entry updated
Automatic update: Entry updated from uniprot information.
Nov. 17, 2018: Protein entry updated
Automatic update: OMIM entry 123866 was added.
Oct. 19, 2018: Additional information
Initial protein addition to the database. This entry was referenced in Bryk and co-workers. (2017).