Complement component 1, q subcomponent, B chain (C1QB)

Complement component 1, q subcomponent, B chain (C1QB) is the B-chain polypeptide of the C1q protein, a critical recognition molecule of the classical complement pathway. C1q is composed of 18 polypeptide chains (six each of A, B, and C), forming a bouquet-like hexameric structure with collagen-like stalks and globular head domains. The C1QB subunit contributes specifically to the globular head, which mediates binding to immunoglobulins (such as IgG and IgM), apoptotic cells, and various endogenous and exogenous ligands. Upon binding to its targets, C1q (including C1QB) triggers activation of the serine proteases C1r and C1s, thus initiating the classical pathway of complement activation leading to opsonization, cell lysis, and immune regulation. Beyond complement activation, C1q and its subunits—including C1QB—participate in the clearance of apoptotic cells, modulation of inflammation, angiogenesis, neurodevelopment, and maintenance of tissue homeostasis. Dysregulation and deficiency of C1q are strongly linked to autoimmune diseases (especially lupus), certain neurodegenerative disorders, pregnancy complications, and pathological angiogenesis[1][2][3][4][5].

Other names

Complement C1q subcomponent subunit BC1QBC1QD2Complement C1q chain BComplement component 1, q subcomponent, B chainComplement component 1, q subcomponent, beta polypeptideComplement component C1q, B chainComplement subcomponent C1q chain B

Inhibition of C1q or C1 complex function to prevent the initiation of the classical complement pathway, aiming to reduce inflammation and tissue damage in autoimmune or inflammatory diseases. Immune modulation by blocking recognition of immune complexes or apoptotic cells.