Cytochrome c oxidase subunit VIb polypeptide 2 is a protein that in humans is encoded by the COX6B2 gene. Cytochrome c oxidase 6B2 is a subunit of the cytochrome c oxidase complex, also known as Complex IV, the last enzyme in the mitochondrialelectron transport chain.[5]
The COX6B2 gene, located on the q arm of chromosome 19 in position 13.42, contains 5 exons and is 5,113 base pairs in length.[5] The protein encoded by the COX6B2 gene weighs 11 kDa and is composed of 88 amino acids.[6][7] The protein is a subunit of Complex IV, a heteromeric complex consisting of 3 catalytic subunits encoded by mitochondrial genes and multiple structural subunits encoded by nuclear genes.[5]
Cytochrome c oxidase (COX) is the terminal enzyme of the mitochondrial respiratory chain. It is a multi-subunit enzyme complex that couples the transfer of electrons from cytochrome c to molecular oxygen and contributes to a proton electrochemical gradient across the inner mitochondrial membrane to drive ATP synthesis via protonmotive force. The mitochondrially-encoded subunits perform the electron transfer of proton pumping activities. The functions of the nuclear-encoded subunits are unknown but they may play a role in the regulation and assembly of the complex.[5]
Summary reaction:
4 Fe2+-cytochrome c + 8 H+in + O2 → 4 Fe3+-cytochrome c + 2 H2O + 4 H+out[8]
^Voet D, Voet JG, Pratt CW (2013). "Chapter 18". Fundamentals of biochemistry: life at the molecular level (4th ed.). Hoboken, NJ: Wiley. pp. 581–620. ISBN978-0-470-54784-7.
Taanman JW, Schrage C, Ponne NJ, Das AT, Bolhuis PA, de Vries H, Agsteribbe E (Sep 1990). "Isolation of cDNAs encoding subunit VIb of cytochrome c oxidase and steady-state levels of coxVIb mRNA in different tissues". Gene. 93 (2): 285–91. doi:10.1016/0378-1119(90)90237-l. PMID2172092.
Hüttemann M, Jaradat S, Grossman LI (Sep 2003). "Cytochrome c oxidase of mammals contains a testes-specific isoform of subunit VIb--the counterpart to testes-specific cytochrome c?". Molecular Reproduction and Development. 66 (1): 8–16. doi:10.1002/mrd.10327. PMID12874793. S2CID45002095.
