Complement factor B is a
protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...
that in humans is encoded by the ''CFB''
gene
In biology, the word gene has two meanings. The Mendelian gene is a basic unit of heredity. The molecular gene is a sequence of nucleotides in DNA that is transcribed to produce a functional RNA. There are two types of molecular genes: protei ...
.
Function
This gene encodes complement factor B, a component of the
alternative pathway
The alternative pathway is a type of cascade reaction of the complement system and is a component of the innate immune system, a natural defense against infections.
The alternative pathway is one of three complement pathways that opsonize and ki ...
of
complement
Complement may refer to:
The arts
* Complement (music), an interval that, when added to another, spans an octave
** Aggregate complementation, the separation of pitch-class collections into complementary sets
* Complementary color, in the visu ...
activation. Factor B circulates in the blood as a single chain polypeptide. Upon activation of the alternative pathway, it is cleaved by complement
factor D yielding the noncatalytic chain Ba and the catalytic subunit Bb. The active subunit Bb is a serine protease that associates with C3b to form the alternative pathway C3 convertase. Bb is involved in the proliferation of preactivated B lymphocytes, while Ba inhibits their proliferation. This gene localizes to the
major histocompatibility complex
The major histocompatibility complex (MHC) is a large Locus (genetics), locus on vertebrate DNA containing a set of closely linked polymorphic genes that code for Cell (biology), cell surface proteins essential for the adaptive immune system. The ...
(
MHC class III
MHC class III is a group of proteins belonging the class of major histocompatibility complex (MHC). Unlike other MHC types such as MHC class I and MHC class II, of which their structure and functions in immune response are well defined, MHC class I ...
) region on
chromosome 6
Chromosome 6 is one of the 23 pairs of chromosomes in humans. People normally have two copies of this chromosome. Chromosome 6 spans nearly 171 million base pairs (the building material of DNA) and represents between 5.5 and 6% of the total DNA i ...
. This cluster includes several genes involved in regulation of the immune reaction. The polyadenylation site of this gene is 421 bp from the 5' end of the gene for complement component 2.
References
Further reading
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External links
GeneReviews/NCBI/NIH/UW entry on Atypical Hemolytic-Uremic Syndrome OMIM entries on Atypical Hemolytic-Uremic Syndrome* The
MEROPS
MEROPS is an online database for peptidases (also known as proteases, proteinases and proteolytic enzymes) and their inhibitors. The classification scheme for peptidases was published by Rawlings & Barrett in 1993, and that for protein inhibito ...
online database for peptidases and their inhibitors
S01.196*
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Complement system
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