C1s Antibody (Polyclonal)

The C1s molecule is a monomeric zymogen protein with a molecular weight of 86 kD. In normal human serum the accepted concentration of C1s is approximately 34 μg/mL. C1s is one of 3 subcomponents that together make the first component of the classical complement pathway, C1. Initiation of the classical complement pathway occurs when C1q binds with IgM or IgG containing antigen-antibody complexes. Upon activation by C1r, the C1s monomer is fragmented into 2 disulfide-linked polypeptide chains, A and B. The enzymatically active site of the C1s molecule is located in the B fragment. With the proteolysis of C1s, C1 becomes active and can then begin to act upon C4 and C2. C1s cleaves C4 into C4a and C4b. C4b then acts as a receptor for C2. Once bound, the C2 becomes a substrate for C1s, which then cleaves C2 into C2a and C2b. C2b remains bound to the C4b creating the C3/C5 convertase of the classical complement pathway.

The Anti-human C1s polyclonal antisera was tested against normal human plasma by double immunodiffusion, one-dimensional immunoelectrophoresis, quantitative radial immunodifussion, and quantitative rocket immunoelectrophoresis. The antiserum was determined to be monospecific for C1s at varying concentrations.