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Prophenoloxidase b hexamer, Marsupenaeus japonicus.

Prophenoloxidase (proPO) is a modified form of the complement response found in some invertebrates, including insects, crabs and worms.[1] It is a copper-containing metalloprotein.[2]

A major innate defense system in invertebrates is the melanization of pathogens and damaged tissues. This important process is controlled by the enzyme phenoloxidase (PO).[3] The conversion of prophenoloxidase to the active form of the enzyme can be brought about by minuscule amounts of molecules such as lipopolysaccharide, peptidoglycan and beta-1,3-glucans from microorganisms.[4]

However, it still has many arguments in the innate immune function, especially in model invertebrate animal.[5] The proPO homologous-protein in mammal also does not have any immune activity. Thus, it might be difficult to conclude its function in immunity.


  1. ^ Beck, Gregory; Habicht, Gail S. (November 1996). "Immunity and the Invertebrates" (PDF). Scientific American. 275 (5): 60–66. Bibcode:1996SciAm.275e..60B. doi:10.1038/scientificamerican1196-60. PMID 8875808.
  2. ^ Sánchez-Aparicio, José-Emilio; Tiessler-Sala, Laura; Velasco-Carneros, Lorea; Roldán-Martín, Lorena; Sciortino, Giuseppe; Maréchal, Jean-Didier (2021-01-25). "BioMetAll: Identifying Metal-Binding Sites in Proteins from Backbone Preorganization". Journal of Chemical Information and Modeling. 61 (1): 311–323. doi:10.1021/acs.jcim.0c00827. ISSN 1549-9596.
  3. ^ Cerenius, L; Söderhäll, K (2004). "The prophenoloxidase-activating system in invertebrates". Immunological Reviews. 198: 116–26. doi:10.1111/j.0105-2896.2004.00116.x. PMID 15199959. S2CID 10614298.
  4. ^ Söderhäll, K; Cerenius, L (1998). "Role of the prophenoloxidase-activating system in invertebrate immunity". Current Opinion in Immunology. 10 (1): 23–8. doi:10.1016/S0952-7915(98)80026-5. PMID 9523106.
  5. ^ Leclerc, V; Reichhart, JM (2006). "Prophenoloxidase activation is not required for survival to microbial infections in Drosophila". EMBO Rep. 7 (2): 231–5. doi:10.1038/sj.embor.7400592. PMC 1369246. PMID 16322759.