The complement system is a part of the larger immune system and three biochemical pathways are present: the classical complement pathway, the alternative pathway, and the mannose-binding lectin pathway.
The biological functions of complement are opsonization and phagocytosis, stimulation of inflammatory reactions and lysis of bacteria.
C1 complex (C1q, C1r and C1s) is the first component of the classical pathway of complement activation which occurs when C1q binds to IgM or IgG complexed with antigens, or when C1q binds directly to the surface of the pathogen. Binding of C1 to immunoglobulins in the form of immune complexes leads to activation of proteases C1r and C1s, and the cleavage of C2 and C4 producing C2a and C4b. C4b and C2a bind to form C3-convertase.
C1q is a hexamer composed of globular heads attached to collagen-like triple-helix tails. The globular heads of C1q specifically bind to the CH2 domain of IgG molecules or the CH3 domain of IgM.
In mammals, hepatocyte is the major source of most C proteins with the exception of C1q, factor D and C7. Interestingly, C1q mRNA is essentially
expressed in spleen, thymus and heart.
C1q knockout mice show a profound impairment in the clearance of apoptotic cells which then accumulate in the kidney leading to glomerulonephritis with immune deposits. Individuals with deficiency of C1q have the highest prevalence of systemic lupus erythematosus.

Western Blot: 4.0 ?g/ml;

Type: Primary
Antigen: C1QBP (complement component 1, q subcomponent binding protein)
Clonality: Monoclonal
Clone: 9A7
Conjugation: Unconjugated
Epitope:
Host: Mouse
Isotype: IgG2b Kappa
Reactivity: Human, Mouse, Rat