C4 binding protein β deficiency

Gene Information


HUGO name: C4BPB


  • C4BP
  • complement component 4 binding protein, beta
  • complement component 4-binding protein, beta
  • C4b-binding protein beta chain precursor


Reference sequences

Chromosomal location


Protein Information


Protein function:

C4BP controls the classical pathway of complement activation. It binds as a cofactor to C3b/C4b inactivator (C3bina), which then hydrolyzes the complement fragment C4b. It also accelerates the degradation of the C4bc2a complex (C3 convertase) by dissociating the complement fragment C2a. It also interacts with anticoagulant Protein S and with Serum Amyloid P component. The beta chain binds Protein S.


Disulfide-linked complex of C4bp alpha and beta chains of 3 possible sorts: a 570 kda complex of 7 alpha chains and 1 beta chain, a 530 kda homoheptamer of alpha chains or a 500 kda complex of 6 alpha chains and 1 beta chain. The central body of the alpha chain homopolymer supports tentacles, each with the binding site for C4b at the end.

Structures (PDB)


Sushi 1 domain: 22-77

    Sushi 2 domain: 80-135

      Sushi 3 domain: 138-192

        Other features

        Signal peptide: 1-17

          C4b-binding protein beta chain: 18-252


            Expression pattern for human

            Tissue Expression (%) Clones
            corresponding non cancerous liver tissue 30.78 14:13909
            colonic mucosa with ulcerative colitus 25.11 1:1218
            liver 22.32 19:26031
            pool, liver+spleen 7.48 15:61327
            pool, placenta 5.19 2:11794
            muscle (skeletal) 3.20 1:9571
            cervix 2.41 2:25325
            pancreas, exocrine 1.43 1:21418
            colon 1.07 3:85835
            pool, lung+testis+B-cell 0.55 1:55714

            Animal models



            C. elegans