CFB
GeneName
CFB
Summary
CFB, also known as factor B or GBG, is a 86 kDa protein that plays a pivotal role in the complement system, which is part of the immune response. It is primarily expressed in the extracellular region and is found in various cellular components such as blood microparticles, extracellular exosomes, and the plasma membrane. CFB is involved in the alternative pathway of complement activation, where it binds to complement component C3 and is cleaved by factor D to form the active component Ba and the C3 convertase. This process is crucial for opsonisation and clearance of pathogens, as well as mediating inflammatory responses. Additionally, CFB exhibits serine-type endopeptidase activity, contributing to proteolytic processes that are important for immune function.
Importance
CFB is relevant to: - The study of complement-mediated immune responses, as it is essential for the activation of the alternative pathway, influencing pathogen clearance and inflammation. - Understanding autoimmune diseases, where dysregulation of the complement system can lead to tissue damage. - Research into infectious diseases, as it plays a role in the response to bacterial infections through complement activation. - The development of therapeutic interventions targeting the complement system in various diseases, including age-related macular degeneration and other inflammatory conditions.
Top Products
For researchers investigating CFB, we recommend two excellent primary antibodies. The first is the well-cited polyclonal antibody, Anti-Factor B antibody (ab192577), which has garnered 11 citations and is highly effective for Western blotting (WB) and immunohistochemistry (IHC). This product is a trusted choice for those looking to study Factor B in various applications. Additionally, we offer the recombinant antibody, Anti-Complement factor B antibody [EPR9288(B)] (ab133765), which is validated for WB. As a recombinant product, it ensures batch-to-batch consistency, making it an ideal option for researchers seeking reliable results in their experiments. The Recombinant Human Factor B protein ELISA Kit (ab274645) is an excellent option for researchers looking to measure Factor B in their experiments.
Abcam Product Citation Summary
The data indicates that CFB is being studied in the context of human urine protein concentrations and mouse liver tissue related to liver injury. The use of both Western blotting and immunohistochemistry suggests a comprehensive approach to understanding the role of CFB in these biological contexts.
Abcam Product Citation Table
Domain
The unliganded VWA domain has an inactive 'locked' conformation whereby the scissile Arg-259|Lys-260 bond is protected from proteolytic activation.
Function
Precursor of the catalytic component of the C3 and C5 convertase complexes of the alternative pathway of the complement system, a cascade of proteins that leads to phagocytosis and breakdown of pathogens and signaling that strengthens the adaptive immune system (PubMed:3638964, PubMed:624565, PubMed:6554279, PubMed:6919543, PubMed:9748277). The alternative complement pathway acts as an amplification loop that enhances other complement pathways (classical, lectin and GZMK) by promoting formation of additional C3 and C5 convertases (PubMed:3638964, PubMed:624565, PubMed:6554279, PubMed:6919543, PubMed:9748277). CFB is cleaved and activated by CFD to generate Ba and Bb chains; Bb chain constituting the catalytic component of the C3 and C5 convertases (PubMed:6769474, PubMed:9748277).
Complement factor B Bb
Serine protease component of the complement C3 and C5 convertase complexes of the alternative complement pathway (PubMed:30643019, PubMed:3638964, PubMed:624565, PubMed:6554279, PubMed:6919543). Following cleavage and activation by factor D (CFD), forms the C3 convertase together with complement C3b (PubMed:3638964, PubMed:624565, PubMed:6554279, PubMed:6919543, PubMed:9748277). As part of the C3 convertase, cleaves and activates C3 into C3a anaphylatoxin and C3b opsonin, the next components of the complement pathways (PubMed:3638964, PubMed:624565, PubMed:6554279, PubMed:6919543, PubMed:9748277). When an additional complement C3b molecule binds to the C3 convertase, forms the C5 convertase, which cleaves and activates C5 into C5a anaphylatoxin and C5b component of the membrane attack complex (PubMed:30643019, PubMed:624565, PubMed:6554279).
Complement factor B Ba
Involved in proliferation and differentiation of preactivated B-lymphocytes, rapid spreading of peripheral blood monocytes, stimulation of lymphocyte blastogenesis and lysis of erythrocytes.
Involvement in disease
Macular degeneration, age-related, 14
ARMD14
A form of age-related macular degeneration, a multifactorial eye disease and the most common cause of irreversible vision loss in the developed world. In most patients, the disease is manifest as ophthalmoscopically visible yellowish accumulations of protein and lipid that lie beneath the retinal pigment epithelium and within an elastin-containing structure known as Bruch membrane.
None
Disease susceptibility may be associated with variants affecting the gene represented in this entry. Haplotype analyzes have identified a statistically significant common risk haplotype and two protective haplotypes. CFB variant His-9 and C2 variant Asp-318, as well as CFB variant Gln-32 and a variant in intron 10 of C2, confer a significantly reduced risk of AMD.
Hemolytic uremic syndrome, atypical, 4
AHUS4
An atypical form of hemolytic uremic syndrome. It is a complex genetic disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, renal failure and absence of episodes of enterocolitis and diarrhea. In contrast to typical hemolytic uremic syndrome, atypical forms have a poorer prognosis, with higher death rates and frequent progression to end-stage renal disease.
None
Disease susceptibility is associated with variants affecting the gene represented in this entry. Susceptibility to the development of atypical hemolytic uremic syndrome can be conferred by mutations in various components of or regulatory factors in the complement cascade system. Other genes may play a role in modifying the phenotype.
Complement factor B deficiency
CFBD
An immunologic disorder characterized by increased susceptibility to bacterial infections, particularly Neisseria infections, due to a defect in the alternative complement pathway.
None
The disease is caused by variants affecting the gene represented in this entry.
Post-translational modifications
Cleaved by CFD following activation of the alternative complement system, generating Ba and Bb chains (PubMed:21205667, PubMed:6769474, PubMed:874324, PubMed:9748277). Cleavage and activation takes place when CFB is already associated with complement C3b (PubMed:21205667).
Sequence Similarities
Belongs to the peptidase S1 family.
Cellular localization
- Secreted
- Complement factor B Bb
- Cell surface
- Recruited to the surface of pathogens by complement C3b opsonin.
Alternative names
BF, BFD, CFB, Complement factor B, C3/C5 convertase, Glycine-rich beta glycoprotein, PBF2, Properdin factor B, GBG