C-terminal cupredoxin domain of Ba3-like heme-copper oxidase subunit II
The ba3 family of heme-copper oxidases are transmembrane protein complexes in the respiratory chains of prokaryotes and some archaea, which catalyze the reduction of O2 and simultaneously pump protons across the membrane. It has been proposed that archaea acquired heme-copper oxidases through gene transfer from gram-positive bacteria. The ba3 family contains oxidases that lack the conserved residues that form the D- and K-pathways in CcO and ubiquinol oxidase. Instead, they contain a potential alternative K-pathway. Additional proton channels have been proposed for this family of oxidases but none have been identified definitively.
Jiyao W et al.(2023). "The conserved domain database in 2023.",