Cytochrome c oxidase subunit 6B2 (COX6B2)

Cytochrome c oxidase subunit 6B2 (COX6B2) is a nuclear-encoded protein component of cytochrome c oxidase (Complex IV), the terminal enzyme of the mitochondrial electron transport chain responsible for catalyzing the reduction of oxygen to water during oxidative phosphorylation[1][4]. COX6B2 is normally expressed specifically in testis tissue but is aberrantly overexpressed in several cancer types, including pancreatic and lung cancers, where its expression correlates with poor prognosis and enhanced metastatic potential[2][5][8]. It plays a structural role within the cytochrome c oxidase complex, specifically mediating the dimerization of the enzyme[8], and is critical for optimal assembly and activity of complex IV, thereby supporting high rates of oxidative phosphorylation. Knockdown of COX6B2 in tumor cells diminishes OXPHOS, induces apoptosis or senescence, and reduces metastatic capacity without affecting primary tumor formation[2][5]. Because of its restricted expression in normal tissue and upregulation in cancer, COX6B2 has emerged as both a functional oncoprotein and a potential biomarker or therapeutic target[2][5].

Other names

COXVIB2CT59Cancer/testis antigen 59COX VIb-2Cytochrome c oxidase subunit VIb isoform 2Cytochrome c oxidase subunit VIb, testis-specific isoformCytochrome c oxidase subunit VIb polypeptide 2 (testis)Cytochrome c oxidase subunit VIb, testes-specific

Metformin accelerates the degradation of COX6B2, resulting in reduced oxidative phosphorylation and metastatic potential in some cancer cells[2].