C8 β-polypeptide deficiency

Gene Information

Names

HUGO name: C8B

Alias(es):

  • Complement component 8, beta polypeptide
  • Complement component C8 beta chain precursor

Localization

Reference sequences

Chromosomal location

Maps

Protein Information

Description

Protein function:

C8 is a constituent of the membrane attack complex. C8 binds to the C5b-7 complex, forming the C5b-8 complex. C5-b8 binds C9 and acts as a catalyst in the polymerization of C9.

Subunit:

C8 is composed of three chains: alpha, beta and gamma. The beta chain binds to the C8 alpha chain and to the C5b-C7 complex, presumably to C5b. It is essential to the incorporation of C8 into the C5b-C8 complex.

Subcellular location:

Secreted

Post-translational modification:

Composition indicates one or two n-linked oligosaccharide chains and no o-glycosylation.

Polymorphism:

The sequence shown is that of allotype C8b.

Structures (PDB)

Domains

Tsp type-1 1 domain: 64-119

    Ldl-receptor class a domain: 120-157

      Egf-like domain: 499-535

        Tsp type-1 2 domain: 542-591

          Expression

          Expression pattern for human

          Tissue Expression (%) Clones
          hepatocellular carcinoma 60.39 12:14226
          corresponding non cancerous liver tissue 20.59 4:13909
          pool, liver+spleen 10.51 9:61327
          liver 8.25 3:26031
          brain 0.26 1:274929

          Animal models

          Mouse

          Fly

          C. elegans