Cytochrome c oxidase subunit 4 isoform 1, mitochondrial (COX4I1)

Cytochrome c oxidase subunit 4 isoform 1, mitochondrial (COX4I1), is a nuclear-encoded regulatory protein and a subunit of the cytochrome c oxidase (Complex IV) enzyme complex located on the inner mitochondrial membrane[1][3][5]. Complex IV is the terminal component of the mitochondrial respiratory chain, catalyzing the transfer of electrons from cytochrome c to molecular oxygen and contributing to the proton electrochemical gradient used for ATP generation[1][3]. COX4I1 is universally expressed, critical for oxidative phosphorylation and energy metabolism, and its expression is regulated by oxygen availability—low oxygen may downregulate COX4I1 in favor of alternative isoforms[1]. Mutations in COX4I1 are associated with severe mitochondrial diseases, including mitochondrial complex IV deficiency and Fanconi anemia, characterized by diverse clinical features such as short stature, poor weight gain, developmental delay, and neurological and muscular complications[1][2][3]. While it participates in a large number of protein–protein interactions within the mitochondrial electron transport chain, no approved therapeutic drugs currently target COX4I1 directly.

Other names

Cytochrome c oxidase subunit 4I1COX4COX4-1COX IV-1COXIVCOXIV-1Cytochrome c oxidase polypeptide IVCytochrome c oxidase subunit IVMC4DN16Cytochrome c oxidase subunit 4 isoform 1

For potential drugs: Modulation of electron transport chain or oxidative phosphorylation (no approved drugs targeting COX4I1 specifically)