COX7B2 encodes cytochrome c oxidase subunit 7B2, a structural component of Complex IV (cytochrome c oxidase) in the mitochondrial electron transport chain. As part of this final respiratory complex, COX7B2 participates in transferring electrons from cytochrome c to molecular oxygen, catalyzing oxygen reduction to water and generating the proton gradient essential for ATP synthesis and oxidative phosphorylation. Mechanistically, COX7B2 functions within the larger Complex IV assembly that accepts electrons via the copper A center and heme A, ultimately delivering them to the binuclear active site containing heme A3 and copper B for oxygen reduction. The protein's functional importance is underscored by evolutionary conservation of key residues, particularly histidine at codon 26 1. COX7B2 demonstrates relevance across multiple disease contexts. A rare His26Gln polymorphism was identified in nasopharyngeal carcinoma families, suggesting potential genetic susceptibility associations 1. COX7B2 appears in metabolism-related prognostic signatures for hepatocellular carcinoma outcome prediction 2 and among Complex IV structural genes with pathogenic potential in breast cancer 3. Downregulation of COX7B2 was identified as a hub gene in non-obstructive azoospermia associated with mitochondrial dysfunction 4. Additionally, SNPs near COX7B2 showed replication in type 2 diabetes susceptibility studies 5. CRISPR-based knockout studies confirmed Cox7b2 is essential for normal spermatozoa production and male fertility in mice 6.