Complement factor B

UniProt P00751 Organism Homo sapiens Gene BF, BFD, CFB EC 3.4.21.47

Also known as: BF, BFD, CFB

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. 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. 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.

Classification

Family (Pfam): PF00084 Sushi, PF00089 Trypsin, PF00092 VWA
InterPro: Compl_C2_B, Complement_B, Peptidase_S1_PA, Peptidase_S1A, Sushi/SCR/CCP_sf, Sushi_SCR_CCP_dom, Trypsin_dom, TRYPSIN_HIS, TRYPSIN_SER, VWF_A, vWFA_dom_sf
Functional cluster: Immunoglobulin-Domain Cell Adhesion Proteins

Experimental structures · PDB · 26

1DLE X-ray 2.10A
1Q0P X-ray 1.80A
1RRK X-ray 2.00A
1RS0 X-ray 2.60A
1RTK X-ray 2.30A
2OK5 X-ray 2.30A
2WIN X-ray 3.90A
2XWB X-ray 3.49A
2XWJ X-ray 4.00A
3HRZ X-ray 2.20A
3HS0 X-ray 3.00A
6QSW X-ray 1.64A
… and 14 more

A predicted model is available from AlphaFold.

Gene Ontology · 12

Disease associations

atypical hemolytic-uremic syndrome with B factor anomaly MONDO:0013042
age related macular degeneration 14 MONDO:0014207
complement factor b deficiency MONDO:0014255

Drugs targeting this protein · 2

IPTACOPAN inhibitor
IPTACOPAN HYDROCHLORIDE inhibitor

Related proteins · sequence + function similarity

Co-cited proteins · studied together in the literature

Complement factor D 4 shared papers
Properdin 4 shared papers
Complement C3 10 shared papers
Cobra venom factor 1 shared papers
Complement C2 2 shared papers
Properdin 1 shared papers
Complement C5 3 shared papers
Complement factor H-related protein 5 1 shared papers
Thrombomodulin 1 shared papers
Complement factor I 1 shared papers
Membrane cofactor protein 1 shared papers
Complement factor H 1 shared papers

Literature · 39 cited papers

Structural Basis for Properdin Oligomerization and Convertase Stimulation in the Human Complement System. Front. Immunol. · 2019
Bacterial killing by complement requires membrane attack complex formation via surface-bound C5 convertases. EMBO J. · 2019
Functional and structural insight into properdin control of complement alternative pathway amplification. EMBO J. · 2017
Deficiency in complement factor B. N. Engl. J. Med. · 2013
Structures of C3b in complex with factors B and D give insight into complement convertase formation. Science · 2010
Mutations in alternative pathway complement proteins in American patients with atypical hemolytic uremic syndrome. Hum. Mutat. · 2010
Insights into complement convertase formation based on the structure of the factor B-cobra venom factor complex. EMBO J. · 2009
Structural and functional implications of the alternative complement pathway C3 convertase stabilized by a staphylococcal inhibitor. Nat. Immunol. · 2009
Glycoproteomics analysis of human liver tissue by combination of multiple enzyme digestion and hydrazide chemistry. J. Proteome Res. · 2009
Factor B structure provides insights into activation of the central protease of the complement system. Nat. Struct. Mol. Biol. · 2007
Gain-of-function mutations in complement factor B are associated with atypical hemolytic uremic syndrome. Proc. Natl. Acad. Sci. U.S.A. · 2007
Variation in factor B (BF) and complement component 2 (C2) genes is associated with age-related macular degeneration. Nat. Genet. · 2006
… and 27 more in the literature graph

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