complement component 4B (Chido blood group)


C4B (may also be known as: None)




This gene encodes the basic form of complement factor 4, part of the classical activation pathway. The protein is expressed as a single chain precursor which is proteolytically cleaved into a trimer of alpha, beta, and gamma chains prior to secretion. The trimer provides a surface for interaction between the antigen-antibody complex and other complement components. The alpha chain may be cleaved to release C4 anaphylatoxin, a mediator of local inflammation. Deficiency of this protein is associated with systemic lupus erythematosus. This gene localizes to the major histocompatibility complex (MHC) class III region on chromosome 6. Varying haplotypes of this gene cluster exist, such that individuals may have 1, 2, or 3 copies of this gene. In addition, this gene exists as a long form and a short form due to the presence or absence of a 6.4 kb endogenous HERV-K retrovirus in intron 9. [provided by RefSeq, Jul 2008]


si:dkey-8k3.2 Danio rerio
C4b Mus musculus
LOC100909666 Rattus norvegicus

Links to external resources

Changes associated with this gene

Identifier Name Type Tissues Organism Gene Data Actions
DAA2147 complement component 4B increases with age Molecular temporal lobe Human C4B 289.9% Increase Gene Expression Level
DAA2150 complement component 4B increases with age Molecular hippocampus Human C4B 466.1% Increase Gene Expression Level
DAA2152 complement component 4B increases with age Molecular parietal lobe Human C4B 444.8% Increase Gene Expression Level
DAA2154 complement component 4B increases with age Molecular frontal lobe Human C4B 895.9% Increase Gene Expression Level

GO Terms

GO IDGO TermGO Category
GO:0006954 inflammatory response biological_process
GO:0006956 complement activation biological_process
GO:0006958 complement activation, classical pathway biological_process
GO:0045087 innate immune response biological_process
GO:0005576 extracellular region cellular_component
GO:0005615 extracellular space cellular_component
GO:0004866 endopeptidase inhibitor activity molecular_function