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Complement component C4-like protein in Atlantic cod (Gadus morhua L.) - Detection in ontogeny and identification of post-translational deimination in serum and extracellular vesicles
- Lange, Sigrun, Kraev, Igor, Magnadóttir, Bergljót, Dodds, Alister W.
- Developmental and comparative immunology 2019 v.101 pp. 103437
- Gadus morhua, antibodies, arginine, blood serum, brain, citrulline, complement, early development, eyes, immunohistochemistry, kidneys, larvae, lectins, liver, mucosa, mucus, muscles, neurons, ontogeny, protein structure, spinal cord
- The complement system is a critical part of teleost immune defences, with complement component C4 forming part of the classical and lectin pathways. Cod C4-like protein was isolated from plasma, specific antibodies generated and C4-like protein was assessed in cod sera, mucus and in extracellular vesicles (EVs) from serum and mucus. Higher levels of C4-like protein were detected in serum- than mucus-derived EVs. Post-translational deimination, caused by conversion of arginine into citrulline, can affect protein structure and function. Here we detected deiminated forms of C4-like protein in cod serum and at lower levels in mucus. C4-like protein was also found in deiminated form at low levels in EVs from both serum and mucus. C4-like protein was assessed by immunohistochemistry in cod larvae and detected in a range of organs including in liver, kidney, gut, muscle, skin and mucus, as well as in neuronal tissues of the brain, spinal cord and eye. This abundance of C4-like protein during early development may indicate roles in tissue remodelling, in addition to immune defences. The presence of deiminated C4-like protein in serum and mucosa, as well as in EVs, may suggest C4 protein moonlighting via post-translational deimination.