Cytochrome c oxidase assembly factor 6 is a protein that in humans is encoded by the COA6gene.[5]Mitochondrial respiratory chainComplex IV, or cytochrome c oxidase, is the component of the respiratory chain that catalyzes the transfer of electrons from intermembrane spacecytochrome c to molecular oxygen in the matrix and as a consequence contributes to the proton gradient involved in mitochondrial ATP synthesis.[6][7] The COA6 gene encodes an assembly factor for mitochondrial complex IV and is a member of the cytochrome c oxidase subunit 6B family.[5][8] This protein is located in the intermembrane space, associating with SCO2 and COX2. It stabilizes newly formed COX2 and is part of the mitochondrial copper relay system.[9]Mutations in this gene result in fatal infantile cardioencephalomyopathy.[8]
The COA6 gene is located on the q arm of chromosome 1 in position 42.2 and spans 10,612 base pairs.[5] The gene produces a 14.1 kDa protein composed of 125 amino acids.[10][11] The COA6 protein is found a complex with TMEM177, COX20, MT-CO2/COX2, COX18, SCO1 and SCO2.[6][7] The protein has a CX9CXnCX10C motif and a CHCH domain, which hints that the protein is most likely a redox protein rather than a copper metallochaperone.[12][13]
The COA6 encodes a protein which is an assembly factor for Complex IV.[5] This protein is specifically required for COX2 biogenesis and stability; the absence of this protein will cause fast turnover of newly synthesized COX2.The presence of a CHCH domain facilitates its function as a thiol-disulfide reductant as it facilitates the transfer of copper from SCO1 to COX2.[12]