CD40:fc (C1QB) Active Protein

C1QB: C1q associates with the proenzymes C1r and C1s to yield C1, the first component of the serum complement system. The collagen-like regions of C1q interact with the Ca(2+)-dependent C1r(2)C1s(2) proenzyme complex, and efficient activation of C1 takes place on interaction of the globular heads of C1q with the Fc regions of IgG or IgM antibody present in immune complexes. Defects in C1QB are a cause of complement component C1q deficiency (C1QD). A rare defect resulting in C1 deficiency and impaired activation of the complement classical pathway. C1 deficiency generally leads to severe immune complex disease with features of systemic lupus erythematosus and glomerulonephritis.

Protein type: Secreted; Secreted, signal peptide

Cellular Component: collagen; extracellular region; complement component C1 complex

Molecular Function: protein homodimerization activity

Biological Process: immune system process; innate immune response; inner ear development; complement activation, classical pathway