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MGP000308

UniProt Annotations

Entry Information

Gene Name	complement factor B
Protein Entry	CFAB_HUMAN
UniProt ID	P00751
Species	Human

Comments

Comment type	Description
Alternative Products	Event=Alternative splicing; Named isoforms=2; Name=1; IsoId=P00751-1; Sequence=Displayed; Name=2; IsoId=P00751-2; Sequence=VSP_005380, VSP_005381;
Catalytic Activity	Cleavage of Arg-\|-Ser bond in complement component C3 alpha-chain to yield C3a and C3b, and Arg-\|-Xaa bond in complement component C5 alpha-chain to yield C5a and C5b.
Disease	Complement factor B deficiency (CFBD) [MIM:615561]: An immunologic disorder characterized by increased susceptibility to bacterial infections, particularly Neisseria infections, due to a defect in the alternative complement pathway. {ECO:0000269\|PubMed:24152280}. Note=The disease is caused by mutations affecting the gene represented in this entry.
Disease	Hemolytic uremic syndrome atypical 4 (AHUS4) [MIM:612924]: 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. {ECO:0000269\|PubMed:17182750, ECO:0000269\|PubMed:20513133}. Note=Disease susceptibility is associated with variations 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.
Domain	The unliganded VWA domain has an inactive 'locked' conformation whereby the scissile Arg-259\|Lys-260 bond is protected from proteolytic activation. {ECO:0000269\|PubMed:17310251}.
Function	Factor B which is part of the alternate pathway of the complement system is cleaved by factor D into 2 fragments: Ba and Bb. Bb, a serine protease, then combines with complement factor 3b to generate the C3 or C5 convertase. It has also been implicated in proliferation and differentiation of preactivated B- lymphocytes, rapid spreading of peripheral blood monocytes, stimulation of lymphocyte blastogenesis and lysis of erythrocytes. Ba inhibits the proliferation of preactivated B-lymphocytes.
Polymorphism	Two major variants, F and S, and 2 minor variants, as well as at least 14 very rare variants, have been identified. The variants His-9 and Gln-32 are associated with a reduced risk of age-related macular degeneration (ARMD) [MIM:603075]. ARMD is a multifactorial eye disease and the most common cause of irreversible vision loss in the developed world.
Similarity	Belongs to the peptidase S1 family. {ECO:0000255\|PROSITE-ProRule:PRU00274}.
Similarity	Contains 1 peptidase S1 domain. {ECO:0000255\|PROSITE- ProRule:PRU00274}.
Similarity	Contains 1 VWFA domain. {ECO:0000255\|PROSITE- ProRule:PRU00219}.
Similarity	Contains 3 Sushi (CCP/SCR) domains. {ECO:0000255\|PROSITE-ProRule:PRU00302}.
Subcellular Location	Secreted.
Subunit	Monomer. {ECO:0000269\|PubMed:19574954}.
Web Resource	Name=SeattleSNPs; URL="http://pga.gs.washington.edu/data/bf/";