C5

Function

Activation of C5 by a C5 convertase initiates the spontaneous assembly of the late complement components, C5-C9, into the membrane attack complex. C5b has a transient binding site for C6. The C5b-C6 complex is the foundation upon which the lytic complex is assembled.

Derived from proteolytic degradation of complement C5, C5 anaphylatoxin is a mediator of local inflammatory process. Binding to the receptor C5AR1 induces a variety of responses including intracellular calcium release, contraction of smooth muscle, increased vascular permeability, and histamine release from mast cells and basophilic leukocytes (PubMed:8182049). C5a is also a potent chemokine which stimulates the locomotion of polymorphonuclear leukocytes and directs their migration toward sites of inflammation.

Involvement in disease

Complement component 5 deficiency

C5D

A rare defect of the complement classical pathway associated with susceptibility to severe recurrent infections, predominantly by Neisseria gonorrhoeae or Neisseria meningitidis.

None

The disease is caused by variants affecting the gene represented in this entry.

An association study of C5 haplotypes and genotypes in individuals with chronic hepatitis C virus infection shows that individuals homozygous for the C5_1 haplotype have a significantly higher stage of liver fibrosis than individuals carrying at least 1 other allele.

Cellular localization

• Secreted

Alternative names

• Complement C5
• C3 and PZP-like alpha-2-macroglobulin domain-containing protein 4
• CPAMD4
• C5

Database links

• entrezGene:735
• entrezGene:727
• entrezGene:729
• entrezGene:730
• entrezGene:731
• omim:120900
• swissprot:P01031
• swissprot:P07357
• swissprot:P10643
• swissprot:P02748
• swissprot:P13671
• swissprot:Q14CJ0
• swissprot:Q27I61

Target type

Proteins

Primary research area

Immunology & Infectious Disease

Molecular weight

188305Da