Complement component 5

Complement component 5 is a protein that in humans is encoded by the C5 gene.^[5]

C5
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1CFA, 1KJS, 1XWE, 3CU7, 3HQA, 3HQB, 3KLS, 3KM9, 3PRX, 3PVM, 4A5W, 4E0S, 4P39, 4UU9, 5I5K, 5HCE, 5HCC, 5HCD
Identifiers
Aliases	C5, C5D, C5a, C5b, CPAMD4, ECLZB, complement component 5, complement C5
External IDs	OMIM: 120900; MGI: 96031; HomoloGene: 20412; GeneCards: C5; OMA:C5 - orthologs
Gene location (Human) Chr. Chromosome 9 (human)[1] Band 9q33.2 Start 120,932,642 bp[1] End 121,075,195 bp[1]
Gene location (Mouse) Chr. Chromosome 2 (mouse)[2] Band 2 B|2 23.22 cM Start 34,873,343 bp[2] End 34,951,450 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in right lobe of liver oocyte body of pancreas secondary oocyte Achilles tendon gonad tibial nerve testicle Descending thoracic aorta ventricular zone Top expressed in left lobe of liver right lung lobe left lung left lung lobe gallbladder granulocyte fetal liver hematopoietic progenitor cell human fetus neural groove embryo More reference expression data BioGPS More reference expression data
Gene ontology Molecular function chemokine activity protein binding endopeptidase inhibitor activity signaling receptor binding Cellular component extracellular region extracellular exosome membrane attack complex extracellular space Biological process G protein-coupled receptor signaling pathway cytolysis complement activation, alternative pathway immune system process complement activation response to stress in utero embryonic development positive regulation of angiogenesis chemotaxis cell surface receptor signaling pathway complement activation, classical pathway positive regulation of vascular endothelial growth factor production inflammatory response regulation of complement activation negative regulation of macrophage chemotaxis negative regulation of endopeptidase activity innate immune response cell chemotaxis Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 727 15139 Ensembl ENSG00000106804 ENSMUSG00000026874 UniProt P01031 P06684 RefSeq (mRNA) NM_001735 NM_001317163 NM_001317164 NM_010406 RefSeq (protein) NP_001304092 NP_001304093 NP_001726 NP_034536 Location (UCSC) Chr 9: 120.93 – 121.08 Mb Chr 2: 34.87 – 34.95 Mb PubMed search [3] [4]
Wikidata
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Complement component 5 is involved in the complement system. It is cleaved into C5a and C5b:

• C5a plays an important role in chemotaxis.^[6]
• C5b forms the first part of the complement membrane attack complex.

Deficiency is thought to cause Leiner's disease.

Function

Complement component 5 is the fifth component of complement, which plays an important role in inflammatory and cell killing processes. This protein is composed of alpha and beta polypeptide chains that are linked by a disulfide bridge. An activation peptide, C5a, which is an anaphylatoxin that possesses potent spasmogenic and chemotactic activity, is derived from the alpha polypeptide via cleavage with a C5-convertase. The C5b macromolecular cleavage product can form a complex with the C6 complement component, and this complex is the basis for formation of the membrane attack complex, which includes additional complement components.^[5]

Clinical significance

Mutations in this gene cause complement component 5 deficiency, a disease where patients show a propensity for severe recurrent infections. Defects in this gene have also been linked to a susceptibility to liver fibrosis and to rheumatoid arthritis.^[5]

Therapeutic applications

The drug eculizumab (trade name Soliris) prevents cleavage of C5 into C5a and C5b.^[7]

Complement system pathway

Membrane attack complex.