Stains & CD markers
Cytochrome c oxidase (COX)

Editorial Board Member: Lauren N. Stuart, M.D., M.B.A.
Sheren Younes, M.D., Ph.D.

Last author update: 1 October 2016
Last staff update: 17 June 2021

Copyright: 2016-2023,, Inc.

PubMed Search: Cytochrome oxidase [title] stains

Sheren Younes, M.D., Ph.D.
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Cite this page: Younes S. Cytochrome c oxidase (COX). website. Accessed June 10th, 2023.
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

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Synthesis and assembly of COX subunits

Maturation and insertion of COX into the respiratory chain

Clinical features
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