Complement Component C5a (C5A) Human Active Protein

C5: 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. Defects in C5 are the cause of 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. 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 (PubMed:15995705).

Protein type: Secreted; Secreted, signal peptide

Chromosomal Location of Human Ortholog: 9q33-q34

Cellular Component: extracellular region

Molecular Function: chemokine activity; protein binding; receptor binding

Biological Process: activation of MAPK activity; cell surface receptor linked signal transduction; chemotaxis; complement activation; G-protein coupled receptor protein signaling pathway; regulation of complement activation; response to stress

Disease: Complement Component 5 Deficiency; Eculizumab, Poor Response To