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Protein

Complement C1q subcomponent subunit A

Gene

C1QA

Organism
Homo sapiens (Human)
Status
Reviewed-Annotation score: Annotation score: 5 out of 5-Experimental evidence at protein leveli

Functioni

C1q associates with the proenzymes C1r and C1s to yield C1, the first component of the serum complement system. The collagen-like regions of C1q interact with the Ca2+-dependent C1r2C1s2 proenzyme complex, and efficient activation of C1 takes place on interaction of the globular heads of C1q with the Fc regions of IgG or IgM antibody present in immune complexes.

GO - Molecular functioni

GO - Biological processi

Complete GO annotation...

Keywords - Biological processi

Complement pathway, Immunity, Innate immunity

Enzyme and pathway databases

BioCyciZFISH:ENSG00000173372-MONOMER.
ReactomeiR-HSA-166663. Initial triggering of complement.
R-HSA-173623. Classical antibody-mediated complement activation.

Names & Taxonomyi

Protein namesi
Recommended name:
Complement C1q subcomponent subunit A
Gene namesi
Name:C1QA
OrganismiHomo sapiens (Human)
Taxonomic identifieri9606 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
Proteomesi
  • UP000005640 Componenti: Chromosome 1

Organism-specific databases

HGNCiHGNC:1241. C1QA.

Subcellular locationi

GO - Cellular componenti

  • collagen trimer Source: UniProtKB-KW
  • complement component C1 complex Source: ProtInc
  • extracellular exosome Source: UniProtKB
  • extracellular region Source: Reactome
Complete GO annotation...

Keywords - Cellular componenti

Secreted

Pathology & Biotechi

Involvement in diseasei

Complement component C1q deficiency (C1QD)
The disease is caused by mutations affecting the gene represented in this entry.
Disease descriptionA disorder caused by impaired activation of the complement classical pathway. It generally leads to severe immune complex disease with features of systemic lupus erythematosus and glomerulonephritis.
See also OMIM:613652

Organism-specific databases

DisGeNETi712.
MalaCardsiC1QA.
MIMi613652. phenotype.
OpenTargetsiENSG00000173372.
Orphaneti169147. Immunodeficiency due to an early component of complement deficiency.
PharmGKBiPA25622.

Chemistry databases

DrugBankiDB00054. Abciximab.
DB00051. Adalimumab.
DB00092. Alefacept.
DB00087. Alemtuzumab.
DB00074. Basiliximab.
DB00112. Bevacizumab.
DB00002. Cetuximab.
DB00111. Daclizumab.
DB00095. Efalizumab.
DB00005. Etanercept.
DB00056. Gemtuzumab ozogamicin.
DB00078. Ibritumomab.
DB00075. Muromonab.
DB00108. Natalizumab.
DB00110. Palivizumab.
DB00073. Rituximab.
DB00081. Tositumomab.
DB00072. Trastuzumab.

Polymorphism and mutation databases

BioMutaiC1QA.
DMDMi399138.

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Signal peptidei1 – 221 PublicationAdd BLAST22
ChainiPRO_000000351723 – 245Complement C1q subcomponent subunit AAdd BLAST223

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Disulfide bondi26Interchain (with C-29 in B chain)
Modified residuei335-hydroxylysine1 Publication1
Glycosylationi33O-linked (Gal...)1 Publication1
Modified residuei394-hydroxyproline1 Publication1
Modified residuei454-hydroxyproline1 Publication1
Modified residuei485-hydroxylysine1 Publication1
Glycosylationi48O-linked (Gal...)1 Publication1
Modified residuei544-hydroxyproline1 Publication1
Modified residuei574-hydroxyproline1 Publication1
Modified residuei675-hydroxylysine1 Publication1
Glycosylationi67O-linked (Gal...)1 Publication1
Modified residuei734-hydroxyproline1 Publication1
Modified residuei794-hydroxyproline1 Publication1
Modified residuei854-hydroxyproline1 Publication1
Modified residuei1005-hydroxylysine1 Publication1
Glycosylationi100O-linked (Gal...)1 Publication1
Glycosylationi146N-linked (GlcNAc...)2 Publications1

Post-translational modificationi

O-linked glycans are assumed to be the Glc-Gal disaccharides typically found as secondary modifications of hydroxylated lysines in collagen-like domains.1 Publication

Keywords - PTMi

Disulfide bond, Glycoprotein, Hydroxylation

Proteomic databases

PaxDbiP02745.
PeptideAtlasiP02745.
PRIDEiP02745.

PTM databases

iPTMnetiP02745.

Expressioni

Gene expression databases

BgeeiENSG00000173372.
CleanExiHS_C1QA.
ExpressionAtlasiP02745. baseline and differential.
GenevisibleiP02745. HS.

Organism-specific databases

HPAiCAB009823.
HPA002350.

Interactioni

Subunit structurei

C1 is a calcium-dependent trimolecular complex of C1q, R and S in the molar ration of 1:2:2. C1q subcomponent is composed of nine subunits, six of which are disulfide-linked dimers of the A and B chains, and three of which are disulfide-linked dimers of the C chain.

Binary interactionsi

WithEntry#Exp.IntActNotes
C1QBP027464EBI-1220209,EBI-2813376
UBQLN2Q9UHD93EBI-1220209,EBI-947187

Protein-protein interaction databases

BioGridi107173. 18 interactors.
IntActiP02745. 15 interactors.
MINTiMINT-1195525.
STRINGi9606.ENSP00000363773.

Structurei

Secondary structure

1245
Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details
Feature keyPosition(s)DescriptionActionsGraphical viewLength
Beta strandi116 – 120Combined sources5
Beta strandi128 – 130Combined sources3
Beta strandi135 – 140Combined sources6
Turni146 – 148Combined sources3
Beta strandi150 – 152Combined sources3
Beta strandi157 – 169Combined sources13
Beta strandi171 – 179Combined sources9
Beta strandi182 – 184Combined sources3
Beta strandi188 – 191Combined sources4
Beta strandi195 – 197Combined sources3
Beta strandi199 – 209Combined sources11
Beta strandi214 – 224Combined sources11
Beta strandi229 – 232Combined sources4
Beta strandi235 – 243Combined sources9

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
1PK6X-ray1.85A112-244[»]
2JG8X-ray2.05A/D112-245[»]
2JG9X-ray1.90A/D112-245[»]
2WNUX-ray2.30A/D112-245[»]
2WNVX-ray1.25A/D112-245[»]
5HKJX-ray1.35A110-245[»]
5HZFX-ray1.55A110-245[»]
ProteinModelPortaliP02745.
SMRiP02745.
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiP02745.

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Domaini31 – 109Collagen-likeAdd BLAST79
Domaini110 – 245C1qPROSITE-ProRule annotationAdd BLAST136

Sequence similaritiesi

Contains 1 C1q domain.PROSITE-ProRule annotation
Contains 1 collagen-like domain.Curated

Keywords - Domaini

Collagen, Repeat, Signal

Phylogenomic databases

eggNOGiENOG410IK45. Eukaryota.
ENOG410YJJD. LUCA.
GeneTreeiENSGT00760000118830.
HOGENOMiHOG000085653.
HOVERGENiHBG108220.
InParanoidiP02745.
KOiK03986.
OMAiVWIEKDP.
OrthoDBiEOG091G0L3Y.
PhylomeDBiP02745.
TreeFamiTF329591.

Family and domain databases

Gene3Di2.60.120.40. 1 hit.
InterProiIPR001073. C1q_dom.
IPR008160. Collagen.
IPR008983. Tumour_necrosis_fac-like_dom.
[Graphical view]
PfamiPF00386. C1q. 1 hit.
PF01391. Collagen. 1 hit.
[Graphical view]
PRINTSiPR00007. COMPLEMNTC1Q.
SMARTiSM00110. C1Q. 1 hit.
[Graphical view]
SUPFAMiSSF49842. SSF49842. 1 hit.
PROSITEiPS50871. C1Q. 1 hit.
[Graphical view]

Sequencei

Sequence statusi: Complete.

Sequence processingi: The displayed sequence is further processed into a mature form.

P02745-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
MEGPRGWLVL CVLAISLASM VTEDLCRAPD GKKGEAGRPG RRGRPGLKGE
60 70 80 90 100
QGEPGAPGIR TGIQGLKGDQ GEPGPSGNPG KVGYPGPSGP LGARGIPGIK
110 120 130 140 150
GTKGSPGNIK DQPRPAFSAI RRNPPMGGNV VIFDTVITNQ EEPYQNHSGR
160 170 180 190 200
FVCTVPGYYY FTFQVLSQWE ICLSIVSSSR GQVRRSLGFC DTTNKGLFQV
210 220 230 240
VSGGMVLQLQ QGDQVWVEKD PKKGHIYQGS EADSVFSGFL IFPSA
Length:245
Mass (Da):26,017
Last modified:July 1, 1993 - v2
Checksum:i8FF6B6AE02D49C4C
GO

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sequence conflicti97P → K AA sequence (PubMed:486087).Curated1
Sequence conflicti103K → P AA sequence (PubMed:486087).Curated1
Sequence conflicti172C → N AA sequence (PubMed:6981411).Curated1
Sequence conflicti178S → W AA sequence (PubMed:6981411).Curated1
Sequence conflicti240 – 243LIFP → ILPGF AA sequence (PubMed:6981411).Curated4

Natural variant

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Natural variantiVAR_02109023E → K.1 PublicationCorresponds to variant rs17887074dbSNPEnsembl.1

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AF135157 mRNA. Translation: AAD32626.1.
AY789471 Genomic DNA. Translation: AAV40828.1.
AL158086 Genomic DNA. Translation: CAI22892.1.
AK311980 mRNA. Translation: BAG34919.1.
AL158086 Genomic DNA. Translation: CAI22893.1.
CH471134 Genomic DNA. Translation: EAW95014.1.
BC030153 mRNA. Translation: AAH30153.1.
BC071986 mRNA. Translation: AAH71986.1.
CCDSiCCDS226.1.
PIRiS14350. C1HUQA.
RefSeqiNP_057075.1. NM_015991.2.
UniGeneiHs.632379.

Genome annotation databases

EnsembliENST00000374642; ENSP00000363773; ENSG00000173372.
ENST00000402322; ENSP00000385564; ENSG00000173372.
GeneIDi712.
KEGGihsa:712.
UCSCiuc001bfy.4. human.

Keywords - Coding sequence diversityi

Polymorphism

Cross-referencesi

Web resourcesi

C1QAbase

C1QA mutation db

SeattleSNPs

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AF135157 mRNA. Translation: AAD32626.1.
AY789471 Genomic DNA. Translation: AAV40828.1.
AL158086 Genomic DNA. Translation: CAI22892.1.
AK311980 mRNA. Translation: BAG34919.1.
AL158086 Genomic DNA. Translation: CAI22893.1.
CH471134 Genomic DNA. Translation: EAW95014.1.
BC030153 mRNA. Translation: AAH30153.1.
BC071986 mRNA. Translation: AAH71986.1.
CCDSiCCDS226.1.
PIRiS14350. C1HUQA.
RefSeqiNP_057075.1. NM_015991.2.
UniGeneiHs.632379.

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
1PK6X-ray1.85A112-244[»]
2JG8X-ray2.05A/D112-245[»]
2JG9X-ray1.90A/D112-245[»]
2WNUX-ray2.30A/D112-245[»]
2WNVX-ray1.25A/D112-245[»]
5HKJX-ray1.35A110-245[»]
5HZFX-ray1.55A110-245[»]
ProteinModelPortaliP02745.
SMRiP02745.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi107173. 18 interactors.
IntActiP02745. 15 interactors.
MINTiMINT-1195525.
STRINGi9606.ENSP00000363773.

Chemistry databases

DrugBankiDB00054. Abciximab.
DB00051. Adalimumab.
DB00092. Alefacept.
DB00087. Alemtuzumab.
DB00074. Basiliximab.
DB00112. Bevacizumab.
DB00002. Cetuximab.
DB00111. Daclizumab.
DB00095. Efalizumab.
DB00005. Etanercept.
DB00056. Gemtuzumab ozogamicin.
DB00078. Ibritumomab.
DB00075. Muromonab.
DB00108. Natalizumab.
DB00110. Palivizumab.
DB00073. Rituximab.
DB00081. Tositumomab.
DB00072. Trastuzumab.

PTM databases

iPTMnetiP02745.

Polymorphism and mutation databases

BioMutaiC1QA.
DMDMi399138.

Proteomic databases

PaxDbiP02745.
PeptideAtlasiP02745.
PRIDEiP02745.

Protocols and materials databases

DNASUi712.
Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENST00000374642; ENSP00000363773; ENSG00000173372.
ENST00000402322; ENSP00000385564; ENSG00000173372.
GeneIDi712.
KEGGihsa:712.
UCSCiuc001bfy.4. human.

Organism-specific databases

CTDi712.
DisGeNETi712.
GeneCardsiC1QA.
HGNCiHGNC:1241. C1QA.
HPAiCAB009823.
HPA002350.
MalaCardsiC1QA.
MIMi120550. gene.
613652. phenotype.
neXtProtiNX_P02745.
OpenTargetsiENSG00000173372.
Orphaneti169147. Immunodeficiency due to an early component of complement deficiency.
PharmGKBiPA25622.
GenAtlasiSearch...

Phylogenomic databases

eggNOGiENOG410IK45. Eukaryota.
ENOG410YJJD. LUCA.
GeneTreeiENSGT00760000118830.
HOGENOMiHOG000085653.
HOVERGENiHBG108220.
InParanoidiP02745.
KOiK03986.
OMAiVWIEKDP.
OrthoDBiEOG091G0L3Y.
PhylomeDBiP02745.
TreeFamiTF329591.

Enzyme and pathway databases

BioCyciZFISH:ENSG00000173372-MONOMER.
ReactomeiR-HSA-166663. Initial triggering of complement.
R-HSA-173623. Classical antibody-mediated complement activation.

Miscellaneous databases

ChiTaRSiC1QA. human.
EvolutionaryTraceiP02745.
GeneWikiiC1QA.
GenomeRNAii712.
PROiP02745.
SOURCEiSearch...

Gene expression databases

BgeeiENSG00000173372.
CleanExiHS_C1QA.
ExpressionAtlasiP02745. baseline and differential.
GenevisibleiP02745. HS.

Family and domain databases

Gene3Di2.60.120.40. 1 hit.
InterProiIPR001073. C1q_dom.
IPR008160. Collagen.
IPR008983. Tumour_necrosis_fac-like_dom.
[Graphical view]
PfamiPF00386. C1q. 1 hit.
PF01391. Collagen. 1 hit.
[Graphical view]
PRINTSiPR00007. COMPLEMNTC1Q.
SMARTiSM00110. C1Q. 1 hit.
[Graphical view]
SUPFAMiSSF49842. SSF49842. 1 hit.
PROSITEiPS50871. C1Q. 1 hit.
[Graphical view]
ProtoNetiSearch...

Entry informationi

Entry nameiC1QA_HUMAN
AccessioniPrimary (citable) accession number: P02745
Secondary accession number(s): B2R4X2, Q5T963
Entry historyi
Integrated into UniProtKB/Swiss-Prot: July 21, 1986
Last sequence update: July 1, 1993
Last modified: November 30, 2016
This is version 183 of the entry and version 2 of the sequence. [Complete history]
Entry statusiReviewed (UniProtKB/Swiss-Prot)
Annotation programChordata Protein Annotation Program
DisclaimerAny medical or genetic information present in this entry is provided for research, educational and informational purposes only. It is not in any way intended to be used as a substitute for professional medical advice, diagnosis, treatment or care.

Miscellaneousi

Keywords - Technical termi

3D-structure, Complete proteome, Direct protein sequencing, Reference proteome

Documents

  1. Human chromosome 1
    Human chromosome 1: entries, gene names and cross-references to MIM
  2. Human entries with polymorphisms or disease mutations
    List of human entries with polymorphisms or disease mutations
  3. Human polymorphisms and disease mutations
    Index of human polymorphisms and disease mutations
  4. MIM cross-references
    Online Mendelian Inheritance in Man (MIM) cross-references in UniProtKB/Swiss-Prot
  5. PDB cross-references
    Index of Protein Data Bank (PDB) cross-references
  6. SIMILARITY comments
    Index of protein domains and families

Similar proteinsi

Links to similar proteins from the UniProt Reference Clusters (UniRef) at 100%, 90% and 50% sequence identity:
100%UniRef100 combines identical sequences and sub-fragments with 11 or more residues from any organism into one UniRef entry.
90%UniRef90 is built by clustering UniRef100 sequences that have at least 90% sequence identity to, and 80% overlap with, the longest sequence (a.k.a seed sequence).
50%UniRef50 is built by clustering UniRef90 seed sequences that have at least 50% sequence identity to, and 80% overlap with, the longest sequence in the cluster.