Recombinant Mouse Complement C1r-A subcomponent (C1ra)

Function

Serine protease component of the complement C1 complex, a multiprotein complex that initiates the classical pathway of the complement system, a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that strengthens the adaptive immune system. C1R catalyzes the first enzymatic step in the classical complement pathway: it is activated by the C1Q subcomplex of the C1 complex, which associates with IgG or IgM immunoglobulins complexed with antigens to form antigen-antibody complexes on the surface of pathogens. Immunoglobulin-binding promotes the autocatalytic cleavage and activation of C1R. Activated C1R then cleaves and activates C1S, the second protease of the classical complement pathway. It is unclear if C1R activates C1S within single, strained C1 complexes or between neighboring C1 complexes on surfaces

Subcellular Location

Secreted; Cell surface

Subunit

Core component of the complement C1 complex, a calcium-dependent complex composed of 1 molecule of the C1Q subcomplex, 2 molecules of C1R and 2 molecules of C1S. The C1Q subcomplex is composed 18 subunits: 3 chains of C1QA, C1QB, and C1QC trimerize to form 6 collagen-like triple helices connected to six globular ligand-recognition modules. Within the C1 complex, C1R is a dimer of identical chains, each of which is activated by cleavage into two chains, heavy and light, connected by disulfide bonds

• Byun S.J. et al. Identification of cDNA encoding a serine protease homologous to human complement C1r precursor from grafted mouse skin. — J. Invest. Dermatol. (2001)
• Garnier G. et al. Complement C1r and C1s genes are duplicated in the mouse: differential expression generates alternative isomorphs in the liver and in the male reproductive system. — Biochem. J. (2003)
• The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). — Genome Res. (2004)
• Bernhard O.K. et al. Enhanced analysis of the mouse plasma proteome using cysteine-containing tryptic glycopeptides. — J. Proteome Res. (2007)