The mitochondrial AOX (alternative oxidase) of the unicellular green alga Chlamydomonas reinhardtii is encoded by two different genes, the Aox1 and Aox2. The? alternative respiratory pathway is comprised of a single homodimeric protein – AOX – and functions as a mechanism to decrease the formation of reactive oxygen species (ROS) produced during respiratory electron transport.? Alternative oxidase expression is? influenced by different stress stimuli.