Cytochrome c oxidase (COX)

Author: Sheren Younes, M.D. (see Authors page)

Editorial Board Review: Lauren Stuart, M.D., M.B.A.

Revised: 14 November 2016, last major update October 2016

Copyright: (c) 2016,, Inc.

PubMed Search: Cytochrome oxidase [title] stains

Page views in 2018: 73
Page views in 2019 to date: 7
Cite this page: Cytochrome c oxidase (COX). website. Accessed January 18th, 2019.
Definition / general
  • Also referred to as Complex IV
  • Unique terminal oxidase of the mitochondrial respiratory chain in mammals
  • Located at the inner mitochondrial membrane
  • Catalyzes the transfer of electrons from ferrocytochrome c to molecular oxygen, for proton transfer across the inner mitochondrial membrane and ATP synthesis
  • Complex made up of 13 subunits
    • Three large, catalytic subunits are encoded with mitochondrial DNA
    • Contain all the heme and metal prosthetic groups needed for catalysis
    • The remaining 10 subunits are encoded by nuclear DNA and transported to mitochondria
  • COX biosynthesis requires many assembly factors that are not a part of the final complex
  • Various isoforms of COX exist according to tissue and developmental stage
  • Exists in an active form as a dimer
  • Several prosthetic groups are required for its catalytic function: 2 heme groups, 2 copper centers, zinc and magnesium

Diagrams / tables

Images hosted on other servers:

Synthesis and assembly of COX subunits

Maturation and insertion of COX into the respiratory chain

Clinical features