C1QA
entrez
712
canonical
uniprot
P02745
canonical
ensembl
ENSG00000173372
resolver
ensp
ENSP00000363773
resolver
ensp
ENSP00000385564
resolver
ensp
ENSP00000416841
resolver
ensp
ENSP00000512133
resolver
ensp
ENSP00000512137
resolver
ensp
ENSP00000552079
resolver
ensp
ENSP00000552080
resolver
ensp
ENSP00000552081
resolver
ensp
ENSP00000552082
resolver
ensp
ENSP00000552083
resolver
ensp
ENSP00000552084
resolver
ensp
ENSP00000635440
resolver
ensp
ENSP00000635441
resolver
enst
ENST00000374642
resolver
enst
ENST00000402322
resolver
enst
ENST00000438241
resolver
enst
ENST00000695740
resolver
enst
ENST00000695744
resolver
enst
ENST00000882020
resolver
enst
ENST00000882021
resolver
enst
ENST00000882022
resolver
enst
ENST00000882023
resolver
enst
ENST00000882024
resolver
enst
ENST00000882025
resolver
enst
ENST00000965381
resolver
enst
ENST00000965382
resolver
genesymbol
C1QA
resolver
hgnc
HGNC:1241
resolver
uniprot
B2R4X2
resolver
uniprot
Q5T963
resolver
uniprot_entry
C1QA_HUMAN
resolver
uniprot_sec
B2R4X2
resolver
uniprot_sec
Q5T963
resolver
activity_regulation
ACTIVITY REGULATION: The C1Q subcomplex is inhibited by sulfated molecules, such as triterpenoid sulfates, heparan sulfate, or chondroitin sulfates. {ECO:0000269|PubMed:20548024, ECO:0000269|PubMed:6218163}.
uniprot
proteins
amino_acid_sequence
MEGPRGWLVLCVLAISLASMVTEDLCRAPDGKKGEAGRPGRRGRPGLKGEQGEPGAPGIRTGIQGLKGDQGEPGPSGNPGKVGYPGPSGPLGARGIPGIKGTKGSPGNIKDQPRPAFSAIRRNPPMGGNVVIFDTVITNQEEPYQNHSGRFVCTVPGYYYFTFQVLSQWEICLSIVSSSRGQVRRSLGFCDTTNKGLFQVVSGGMVLQLQQGDQVWVEKDPKKGHIYQGSEADSVFSGFLIFPSA
uniprot
proteins
disease_involvement
DISEASE: C1q deficiency 1 (C1QD1) [MIM:613652]: An autosomal recessive disorder caused by impaired activation of the complement classical pathway. It generally leads to severe immune complex disease characterized by recurrent skin lesions, chronic infections, an increased risk of systemic lupus erythematosus, and glomerulonephritis. {ECO:0000269|PubMed:9777412}. Note=The disease is caused by variants affecting the gene represented in this entry.
uniprot
proteins
function
FUNCTION: Core component of the complement C1 complex, a multiprotein complex that initiates the classical 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:12847249, PubMed:19006321, PubMed:24626930, PubMed:29449492, PubMed:3258649, PubMed:34155115, PubMed:6249812, PubMed:6776418). The classical complement pathway is initiated by the C1Q subcomplex of the C1 complex, which specifically binds IgG or IgM immunoglobulins complexed with antigens, forming antigen-antibody complexes on the surface of pathogens: C1QA, together with C1QB and C1QC, specifically recognizes and binds the Fc regions of IgG or IgM via its C1q domain (PubMed:12847249, PubMed:19006321, PubMed:24626930, PubMed:29449492, PubMed:3258649, PubMed:6776418). Immunoglobulin-binding activates the proenzyme C1R, which cleaves C1S, initiating the proteolytic cascade of the complement system (PubMed:29449492). The C1Q subcomplex is activated by a hexamer of IgG complexed with antigens, while it is activated by a pentameric IgM (PubMed:19706439, PubMed:24626930, PubMed:29449492). The C1Q subcomplex also recognizes and binds phosphatidylserine exposed on the surface of cells undergoing programmed cell death, possibly promoting activation of the complement system (PubMed:18250442). {ECO:0000269|PubMed:12847249, ECO:0000269|PubMed:18250442, ECO:0000269|PubMed:19006321, ECO:0000269|PubMed:19706439, ECO:0000269|PubMed:24626930, ECO:0000269|PubMed:29449492, ECO:0000269|PubMed:3258649, ECO:0000269|PubMed:34155115, ECO:0000269|PubMed:6249812, ECO:0000269|PubMed:6776418}.
uniprot
proteins
mass_dalton
26017
uniprot
proteins
mutagenesis
MUTAGEN 81; /note="K->A: In LysA59; impaired ability to associate with C1R and C1S."; /evidence="ECO:0000269|PubMed:23650384"; MUTAGEN 222; /note="K->E: Decreases binding to IgM and IgG."; /evidence="ECO:0000269|PubMed:19006321
uniprot
proteins
post_translational_modification
PTM: O-linked glycans are assumed to be the Glc-Gal disaccharides typically found as secondary modifications of hydroxylated lysines in collagen-like domains. {ECO:0000269|PubMed:486087}.
uniprot
proteins
pubmed
12847249
uniprot
proteins
pubmed
12960167
uniprot
proteins
pubmed
14702039
uniprot
proteins
pubmed
15489334
uniprot
proteins
pubmed
16335952
uniprot
proteins
pubmed
16710414
uniprot
proteins
pubmed
1706597
uniprot
proteins
pubmed
18250442
uniprot
proteins
pubmed
19006321
uniprot
proteins
pubmed
19159218
uniprot
proteins
pubmed
19706439
uniprot
proteins
pubmed
20548024
uniprot
proteins
pubmed
23650384
uniprot
proteins
pubmed
23720782
uniprot
proteins
pubmed
24626930
uniprot
proteins
pubmed
28325905
uniprot
proteins
pubmed
29449492
uniprot
proteins
pubmed
29563915
uniprot
proteins
pubmed
2988513
uniprot
proteins
pubmed
3258649
uniprot
proteins
pubmed
34155115
uniprot
proteins
pubmed
486087
uniprot
proteins
pubmed
6218163
uniprot
proteins
pubmed
6249812
uniprot
proteins
pubmed
6776418
uniprot
proteins
pubmed
6952210
uniprot
proteins
pubmed
6981411
uniprot
proteins
pubmed
708376
uniprot
proteins
pubmed
9324355
uniprot
proteins
pubmed
9777412
uniprot
proteins
sequence_length
245
uniprot
proteins
subcellular_location
SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:18250442, ECO:0000269|PubMed:29449492}. Cell surface {ECO:0000269|PubMed:34155115}. Note=Specifically binds IgG or IgM immunoglobulins complexed with antigens, forming antigen-antibody complexes on the surface of pathogens. {ECO:0000269|PubMed:34155115}.
uniprot
proteins