Mitochondria of the protozoa Acanthamoeba castellanii possess a cyanide-insensitive oxidase cross-reacting with monoclonal antibodies raised against the plant alternative oxidase. Immunoblotting revealed three monomeric forms (38, 35, and 32 kDa) and very low amounts of a single 65 kDa dimeric form. Cross-linking studies suggest that while in plants the alternative oxidase occurs as a diner, in amoeba it functions as a monomer. Immunologically detectable protein levels change with the age of amoeba cell culture. Increased amounts of the 35 kDa protein are accompanied by an increase in the activity of cyanide-resistant respiration.
Jarmuszkiewicz, W., Wagner, A. M., Wagner, M. J., & Hryniewiecka, L. (1997). Immunological identification of the alternative oxidase of Acanthamoeba castellanii mitochondria. FEBS Letters, 411(1), 110–114. https://doi.org/10.1016/S0014-5793(97)00676-5