Proteases of the complement system.

  title={Proteases of the complement system.},
  author={Robert B Sim and Stefanos A. Tsiftsoglou},
  journal={Biochemical Society transactions},
  volume={32 Pt 1},
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… 

Figures and Tables from this paper

Complement Protease C1r
Serine Proteases in the Lectin Pathway of the Complement System
This chapter presents an overview of the complement system focusing on the characterization of MASPs and its genes, as well as its functions in the immune response.
Complement Proteins as Soluble Pattern Recognition Receptors for Pathogenic Viruses
This review focuses on complement-dependent and -independent interactions of complement components (especially C1q, C4b-binding protein, properdin, factor H, Mannose-binding lectin, and Ficolins) with several viruses and their consequences.
Analogous Interactions in Initiating Complexes of the Classical and Lectin Pathways of Complement1
This work has analyzed binding between human C1q, C1r, and C1s, which associate to form C1, using full-length and truncated protease components and proposes a new model using mannan-binding Lectin-mannan-binding lectin-associated serine protease interactions as a template.
Proprotein Convertases and the Complement System
It is pointed out that the proper functioning of the complement system intimately depends on the action of proprotein convertases, moreover indirectly, through the constitutive activation of pro-factor D by MASP-3, the activity of the alternative pathway also depends on a PC present in the blood.
Engineering Novel Complement Activity into a Pulmonary Surfactant Protein*
Novel complement activity is introduced concurrently with MASP binding in SP-A but is uncontrolled and occurs even in the absence of a carbohydrate target, meaning the active rather than the zymogen state is default in lectin·MASP complexes and must be inhibited through additional regions in circulating MBLs until triggered by pathogen recognition.
Structural biology of the membrane attack complex.
Recent structures of MAC components and homologous proteins significantly increased the understanding of oligomerisation, membrane association and integration, shedding light onto the molecular mechanism of this important branch of the innate immune system.


Complement, A Practical Approach (Dodds
  • A.W. and Sim, R.B., eds.),
  • 1997