Proteases of the complement system.

@article{Sim2004ProteasesOT,
  title={Proteases of the complement system.},
  author={Robert B Sim and Stefanos A. Tsiftsoglou},
  journal={Biochemical Society transactions},
  year={2004},
  volume={32 Pt 1},
  pages={
          21-7
        }
}
The complement system is a group of about 35 soluble and cell-surface proteins which interact to recognize, opsonize and clear or kill invading micro-organisms or altered host cells (e.g. apoptotic or necrotic cells). Complement is a major part of the innate immune system. Recognition proteins such as C1q, MBL (mannan-binding lectin) and ficolins bind to targets via charge or sugar arrays. Binding causes activation of a series of serine protease proenzymes, such as C1r, C1s and MASP2 (MBL… 

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