Complement component C1s (human) monoclonal antibody (9)

C1s proenzyme is a 79.8kDa glycoprotein produced primarily by hepatocytes but also by other cells. The proenzyme is produced as a single-chain polypeptide of 688 amino acids. Upon activation, the peptide is cleaved between R437 and I438, producing an activated enzyme consisting of two disulfide-linked chains, A chain (52.2kDa) and B chain (27.7kDa). The calcium-dependent catalytic subunit of the C1 complex (C1q, C1r, C1s) is comprised of two C1s and two C1r molecules, and this serine protease tetramer is responsible for the initial steps in the cleavage of C4 and C2 in the classical complement pathway.