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Protein

Complement C1q subcomponent subunit B

Gene

C1QB

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:ENSG00000173369-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 B
Gene namesi
Name:C1QB
OrganismiHomo sapiens (Human)
Taxonomic identifieri9606 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
Proteomesi
  • UP000005640 Componenti: Chromosome 1

Organism-specific databases

HGNCiHGNC:1242. C1QB.

Subcellular locationi

GO - Cellular componenti

  • blood microparticle Source: UniProtKB
  • 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)1 Publication
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
Feature keyPosition(s)DescriptionActionsGraphical viewLength
Natural variantiVAR_00854142G → D in C1QD. 1 Publication1

Keywords - Diseasei

Disease mutation

Organism-specific databases

DisGeNETi713.
MalaCardsiC1QB.
MIMi613652. phenotype.
OpenTargetsiENSG00000173369.
Orphaneti169147. Immunodeficiency due to an early component of complement deficiency.
PharmGKBiPA25623.

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

BioMutaiC1QB.
DMDMi298286922.

PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Signal peptidei1 – 272 PublicationsAdd BLAST27
ChainiPRO_000000352128 – 253Complement C1q subcomponent subunit BAdd BLAST226

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Modified residuei28Pyrrolidone carboxylic acid1 Publication1
Disulfide bondi31Interchain (with C-26 in chain A)1 Publication
Modified residuei354-hydroxyproline1 Publication1
Modified residuei384-hydroxyproline1 Publication1
Modified residuei414-hydroxyproline1 Publication1
Modified residuei534-hydroxyproline1 Publication1
Modified residuei564-hydroxyproline1 Publication1
Modified residuei595-hydroxylysine1 Publication1
Modified residuei625-hydroxylysine1 Publication1
Modified residuei654-hydroxyproline1 Publication1
Modified residuei775-hydroxylysine1 Publication1
Modified residuei834-hydroxyproline1 Publication1
Modified residuei864-hydroxyproline1 Publication1
Modified residuei925-hydroxylysine1 Publication1
Modified residuei985-hydroxylysine1 Publication1
Modified residuei1014-hydroxyproline1 Publication1
Modified residuei1044-hydroxyproline1 Publication1
Modified residuei1074-hydroxyproline1 Publication1
Modified residuei1105-hydroxylysine1 Publication1

Post-translational modificationi

Hydroxylated on lysine and proline residues. Hydroxylated lysine residues can be glycosylated. Human C1Q contains up to 68.3 hydroxylysine-galactosylglucose residues and up to 2.5 hydroxylysine-galactose per molecule. Total percentage hydroxylysine residues glycosylated is 86.4%.3 Publications

Keywords - PTMi

Disulfide bond, Glycoprotein, Hydroxylation, Pyrrolidone carboxylic acid

Proteomic databases

PaxDbiP02746.
PeptideAtlasiP02746.
PRIDEiP02746.

PTM databases

iPTMnetiP02746.
PhosphoSitePlusiP02746.

Expressioni

Gene expression databases

BgeeiENSG00000173369.
CleanExiHS_C1QB.
ExpressionAtlasiP02746. baseline and differential.
GenevisibleiP02746. HS.

Organism-specific databases

HPAiHPA052116.

Interactioni

Subunit structurei

C1 is a calcium-dependent trimolecular complex of C1q, c1r and C1s 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.1 Publication

Binary interactionsi

WithEntry#Exp.IntActNotes
C1QAP027454EBI-2813376,EBI-1220209

Protein-protein interaction databases

BioGridi107174. 18 interactors.
IntActiP02746. 8 interactors.
MINTiMINT-6629999.
STRINGi9606.ENSP00000313967.

Structurei

Secondary structure

1253
Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details
Feature keyPosition(s)DescriptionActionsGraphical viewLength
Helixi118 – 120Combined sources3
Beta strandi123 – 127Combined sources5
Beta strandi144 – 149Combined sources6
Turni155 – 157Combined sources3
Beta strandi159 – 161Combined sources3
Beta strandi166 – 178Combined sources13
Beta strandi180 – 190Combined sources11
Beta strandi192 – 199Combined sources8
Beta strandi202 – 204Combined sources3
Beta strandi206 – 216Combined sources11
Beta strandi221 – 230Combined sources10
Beta strandi241 – 249Combined sources9

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
1PK6X-ray1.85B119-250[»]
2JG8X-ray2.05B/E118-253[»]
2JG9X-ray1.90B/E118-253[»]
2WNUX-ray2.30B/E118-253[»]
2WNVX-ray1.25B/E118-253[»]
5HKJX-ray1.35A117-253[»]
5HZFX-ray1.55A117-253[»]
ProteinModelPortaliP02746.
SMRiP02746.
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiP02746.

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Domaini37 – 86Collagen-like 1Add BLAST50
Domaini60 – 114Collagen-like 2Add BLAST55
Domaini117 – 253C1qPROSITE-ProRule annotationAdd BLAST137

Sequence similaritiesi

Contains 1 C1q domain.PROSITE-ProRule annotation
Contains 2 collagen-like domains.Curated

Keywords - Domaini

Collagen, Repeat, Signal

Phylogenomic databases

eggNOGiENOG410IWVM. Eukaryota.
ENOG4111MQB. LUCA.
GeneTreeiENSGT00760000118830.
HOGENOMiHOG000085653.
HOVERGENiHBG108220.
InParanoidiP02746.
KOiK03987.
OMAiFFTYHAS.
OrthoDBiEOG091G0L3Y.
PhylomeDBiP02746.
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. 2 hits.
[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.

P02746-1 [UniParc]FASTAAdd to basket

« Hide

        10         20         30         40         50
MMMKIPWGSI PVLMLLLLLG LIDISQAQLS CTGPPAIPGI PGIPGTPGPD
60 70 80 90 100
GQPGTPGIKG EKGLPGLAGD HGEFGEKGDP GIPGNPGKVG PKGPMGPKGG
110 120 130 140 150
PGAPGAPGPK GESGDYKATQ KIAFSATRTI NVPLRRDQTI RFDHVITNMN
160 170 180 190 200
NNYEPRSGKF TCKVPGLYYF TYHASSRGNL CVNLMRGRER AQKVVTFCDY
210 220 230 240 250
AYNTFQVTTG GMVLKLEQGE NVFLQATDKN SLLGMEGANS IFSGFLLFPD

MEA
Length:253
Mass (Da):26,722
Last modified:June 15, 2010 - v3
Checksum:iD80C753C0D430EDC
GO

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Sequence conflicti28Q → E AA sequence (PubMed:708376).Curated1
Sequence conflicti85N → D AA sequence (PubMed:708376).Curated1
Sequence conflicti100G → P AA sequence (PubMed:708376).Curated1
Sequence conflicti100G → P AA sequence (PubMed:486087).Curated1

Natural variant

Feature keyPosition(s)DescriptionActionsGraphical viewLength
Natural variantiVAR_00854142G → D in C1QD. 1 Publication1
Natural variantiVAR_035551123A → T in a breast cancer sample; somatic mutation. 1 PublicationCorresponds to variant rs776292843dbSNPEnsembl.1

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AL158086 Genomic DNA. Translation: CAI22896.1.
BC008983 mRNA. Translation: AAH08983.1.
X03084 mRNA. Translation: CAA26880.1.
M36278 mRNA. Translation: AAC41692.1.
CCDSiCCDS228.1.
PIRiB23422. C1HUQB.
RefSeqiNP_000482.3. NM_000491.3.
XP_011540361.1. XM_011542059.2.
UniGeneiHs.8986.

Genome annotation databases

EnsembliENST00000314933; ENSP00000313967; ENSG00000173369.
GeneIDi713.
KEGGihsa:713.
UCSCiuc001bgd.3. human.

Keywords - Coding sequence diversityi

Polymorphism

Cross-referencesi

Web resourcesi

C1QBbase

C1QB mutation db

Sequence databases

Select the link destinations:
EMBLi
GenBanki
DDBJi
Links Updated
AL158086 Genomic DNA. Translation: CAI22896.1.
BC008983 mRNA. Translation: AAH08983.1.
X03084 mRNA. Translation: CAA26880.1.
M36278 mRNA. Translation: AAC41692.1.
CCDSiCCDS228.1.
PIRiB23422. C1HUQB.
RefSeqiNP_000482.3. NM_000491.3.
XP_011540361.1. XM_011542059.2.
UniGeneiHs.8986.

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
PDB entryMethodResolution (Å)ChainPositionsPDBsum
1PK6X-ray1.85B119-250[»]
2JG8X-ray2.05B/E118-253[»]
2JG9X-ray1.90B/E118-253[»]
2WNUX-ray2.30B/E118-253[»]
2WNVX-ray1.25B/E118-253[»]
5HKJX-ray1.35A117-253[»]
5HZFX-ray1.55A117-253[»]
ProteinModelPortaliP02746.
SMRiP02746.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi107174. 18 interactors.
IntActiP02746. 8 interactors.
MINTiMINT-6629999.
STRINGi9606.ENSP00000313967.

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

iPTMnetiP02746.
PhosphoSitePlusiP02746.

Polymorphism and mutation databases

BioMutaiC1QB.
DMDMi298286922.

Proteomic databases

PaxDbiP02746.
PeptideAtlasiP02746.
PRIDEiP02746.

Protocols and materials databases

DNASUi713.
Structural Biology KnowledgebaseSearch...

Genome annotation databases

EnsembliENST00000314933; ENSP00000313967; ENSG00000173369.
GeneIDi713.
KEGGihsa:713.
UCSCiuc001bgd.3. human.

Organism-specific databases

CTDi713.
DisGeNETi713.
GeneCardsiC1QB.
HGNCiHGNC:1242. C1QB.
HPAiHPA052116.
MalaCardsiC1QB.
MIMi120570. gene.
613652. phenotype.
neXtProtiNX_P02746.
OpenTargetsiENSG00000173369.
Orphaneti169147. Immunodeficiency due to an early component of complement deficiency.
PharmGKBiPA25623.
GenAtlasiSearch...

Phylogenomic databases

eggNOGiENOG410IWVM. Eukaryota.
ENOG4111MQB. LUCA.
GeneTreeiENSGT00760000118830.
HOGENOMiHOG000085653.
HOVERGENiHBG108220.
InParanoidiP02746.
KOiK03987.
OMAiFFTYHAS.
OrthoDBiEOG091G0L3Y.
PhylomeDBiP02746.
TreeFamiTF329591.

Enzyme and pathway databases

BioCyciZFISH:ENSG00000173369-MONOMER.
ReactomeiR-HSA-166663. Initial triggering of complement.
R-HSA-173623. Classical antibody-mediated complement activation.

Miscellaneous databases

ChiTaRSiC1QB. human.
EvolutionaryTraceiP02746.
GenomeRNAii713.
PROiP02746.
SOURCEiSearch...

Gene expression databases

BgeeiENSG00000173369.
CleanExiHS_C1QB.
ExpressionAtlasiP02746. baseline and differential.
GenevisibleiP02746. 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. 2 hits.
[Graphical view]
PRINTSiPR00007. COMPLEMNTC1Q.
SMARTiSM00110. C1Q. 1 hit.
[Graphical view]
SUPFAMiSSF49842. SSF49842. 1 hit.
PROSITEiPS50871. C1Q. 1 hit.
[Graphical view]
ProtoNetiSearch...

Entry informationi

Entry nameiC1QB_HUMAN
AccessioniPrimary (citable) accession number: P02746
Secondary accession number(s): Q5T959, Q96H17
Entry historyi
Integrated into UniProtKB/Swiss-Prot: July 21, 1986
Last sequence update: June 15, 2010
Last modified: November 30, 2016
This is version 184 of the entry and version 3 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.