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C3 (complement)

Complement component 3
PDB rendering based on 1c3d.
Available structures: 1c3d, 1ghq, 1w2s, 2a73, 2a74, 2b39, 2gox, 2hr0, 2i07, 2ice, 2icf
Symbol(s) C3; ASP; CPAMD1
External IDs OMIM: 120700 MGI: 88227 Homologene: 68031
Human Mouse
Entrez 718 12266
Ensembl na ENSMUSG00000024164
Uniprot na Q207D2
Refseq NM_000064 (mRNA)
NP_000055 (protein)
NM_009778 (mRNA)
NP_033908 (protein)
Location na Chr 17: 56.89 - 56.91 Mb
Pubmed search [1] [2]

In immunology, soluble C3-convertase, also known as iC3Bb, catalyzes the proteolytic cleavage of C3 into C3a and C3b as part of the alternative complement system.



C3a plays an important role in chemotaxis, though not as important a role as C5a.[1]

It is also an anaphylatoxin.


C3b may bind to microbial cell surfaces within an organism's body. This can lead to the production of surface-bound C3 convertase and thus more C3b components. Also known as C3bBb, this convertase is similar to soluble C3-convertase except that it is membrane bound.

Alternatively, bound C3b may aid in opsonization of the microbe by macrophages.[1] Complement receptor 1 or CR1 on macrophages allows the engaging of C3b covered microbes.

C3b is cleaved into C3c and C3d.

See also


  1. ^ a b Immunology at MCG 1/phagocyt

Further reading

  • Matsuyama W, Nakagawa M, Takashima H, et al. (2002). "Molecular analysis of hereditary deficiency of the third component of complement (C3) in two sisters.". Intern. Med. 40 (12): 1254-8. PMID 11813855.

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "C3_(complement)". A list of authors is available in Wikipedia.
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