UniProt functional annotation for P06681



	UniProt functional annotation for P06681

UniProt code: P06681.

Organism: Homo sapiens (Human).

Taxonomy: Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo.

Function: Component C2 which is part of the classical pathway of the complement system is cleaved by activated factor C1 into two fragments: C2b and C2a. C2a, a serine protease, then combines with complement factor C4b to generate the C3 or C5 convertase.

Catalytic activity: Reaction=Selective cleavage of Arg-|-Ser bond in complement component C3 alpha-chain to form C3a and C3b, and Arg-|-Xaa bond in complement component C5 alpha-chain to form C5a and C5b.; EC=3.4.21.43;

Subunit: C2a interacts with Schistosoma haematobium TOR (via N-terminal extracellular domain). This results in inhibition of the classical and lectin pathway of complement activation, probably due to interference with binding of C2a to C4b such that C3 convertase cannot be formed. This infers resistance to complement-mediated cell lysis, allowing parasite survival and infection. {ECO:0000269|PubMed:10734221}.

Subcellular location: Secreted.

Domain: The MIDAS-like motif in the VWFA domain binds divalent metal cations.

Disease: Macular degeneration, age-related, 14 (ARMD14) [MIM:615489]: 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. {ECO:0000269|PubMed:16518403}. Note=Disease susceptibility may be associated with variants affecting the gene represented in this entry. Haplotype analyses 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. {ECO:0000269|PubMed:16518403}.

Disease: Complement component 2 deficiency (C2D) [MIM:217000]: A rare defect of the complement classical pathway associated with the development of autoimmune disorders, mainly systemic lupus erythematosus. Skin and joint manifestations are common and renal disease is relatively rare. Patients with complement component 2 deficiency are also reported to have recurrent invasive infections. {ECO:0000269|PubMed:8621452, ECO:0000269|PubMed:9670930}. Note=The disease is caused by variants affecting the gene represented in this entry.

Miscellaneous: C2 is a major histocompatibility complex class-III protein.

Similarity: Belongs to the peptidase S1 family. {ECO:0000255|PROSITE- ProRule:PRU00274}.

Annotations taken from UniProtKB at the EBI.


Organism:		Homo sapiens (Human).
Taxonomy:		Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia; Eutheria; Euarchontoglires; Primates; Haplorrhini; Catarrhini; Hominidae; Homo.



Function:		Component C2 which is part of the classical pathway of the complement system is cleaved by activated factor C1 into two fragments: C2b and C2a. C2a, a serine protease, then combines with complement factor C4b to generate the C3 or C5 convertase.


Catalytic activity:		Reaction=Selective cleavage of Arg-\|-Ser bond in complement component C3 alpha-chain to form C3a and C3b, and Arg-\|-Xaa bond in complement component C5 alpha-chain to form C5a and C5b.; EC=3.4.21.43;
Subunit:		C2a interacts with Schistosoma haematobium TOR (via N-terminal extracellular domain). This results in inhibition of the classical and lectin pathway of complement activation, probably due to interference with binding of C2a to C4b such that C3 convertase cannot be formed. This infers resistance to complement-mediated cell lysis, allowing parasite survival and infection. {ECO:0000269\|PubMed:10734221}.
Subcellular location:		Secreted.
Domain:		The MIDAS-like motif in the VWFA domain binds divalent metal cations.
Disease:		Macular degeneration, age-related, 14 (ARMD14) [MIM:615489]: 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. {ECO:0000269\|PubMed:16518403}. Note=Disease susceptibility may be associated with variants affecting the gene represented in this entry. Haplotype analyses 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. {ECO:0000269\|PubMed:16518403}.
Disease:		Complement component 2 deficiency (C2D) [MIM:217000]: A rare defect of the complement classical pathway associated with the development of autoimmune disorders, mainly systemic lupus erythematosus. Skin and joint manifestations are common and renal disease is relatively rare. Patients with complement component 2 deficiency are also reported to have recurrent invasive infections. {ECO:0000269\|PubMed:8621452, ECO:0000269\|PubMed:9670930}. Note=The disease is caused by variants affecting the gene represented in this entry.
Miscellaneous:		C2 is a major histocompatibility complex class-III protein.
Similarity:		Belongs to the peptidase S1 family. {ECO:0000255\|PROSITE- ProRule:PRU00274}.