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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 - Biological processi

Complete GO annotation...

Keywords - Biological processi

Complement pathway, Immunity, Innate immunity

Enzyme and pathway databases

ReactomeiREACT_7956. Classical antibody-mediated complement activation.
REACT_8024. Initial triggering of complement.

Names & Taxonomyi

Protein namesi
Recommended name:
Complement C1q subcomponent subunit B
Gene namesi
Name:C1QB
OrganismiHomo sapiens (Human)
Taxonomic identifieri9606 [NCBI]
Taxonomic lineageiEukaryotaMetazoaChordataCraniataVertebrataEuteleostomiMammaliaEutheriaEuarchontogliresPrimatesHaplorrhiniCatarrhiniHominidaeHomo
ProteomesiUP000005640 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)LengthDescriptionGraphical viewFeature identifierActions
Natural varianti42 – 421G → D in C1QD. 1 Publication
VAR_008541

Keywords - Diseasei

Disease mutation

Organism-specific databases

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

Chemistry

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)LengthDescriptionGraphical viewFeature identifierActions
Signal peptidei1 – 27272 PublicationsAdd
BLAST
Chaini28 – 253226Complement C1q subcomponent subunit BPRO_0000003521Add
BLAST

Amino acid modifications

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Modified residuei28 – 281Pyrrolidone carboxylic acid1 Publication
Disulfide bondi31 – 31Interchain (with C-26 in chain A)1 Publication
Modified residuei35 – 3514-hydroxyproline1 Publication
Modified residuei38 – 3814-hydroxyproline1 Publication
Modified residuei41 – 4114-hydroxyproline1 Publication
Modified residuei53 – 5314-hydroxyproline1 Publication
Modified residuei56 – 5614-hydroxyproline1 Publication
Modified residuei59 – 5915-hydroxylysine1 Publication
Modified residuei62 – 6215-hydroxylysine1 Publication
Modified residuei65 – 6514-hydroxyproline1 Publication
Modified residuei77 – 7715-hydroxylysine1 Publication
Modified residuei83 – 8314-hydroxyproline1 Publication
Modified residuei86 – 8614-hydroxyproline1 Publication
Modified residuei92 – 9215-hydroxylysine1 Publication
Modified residuei98 – 9815-hydroxylysine1 Publication
Modified residuei101 – 10114-hydroxyproline1 Publication
Modified residuei104 – 10414-hydroxyproline1 Publication
Modified residuei107 – 10714-hydroxyproline1 Publication
Modified residuei110 – 11015-hydroxylysine1 Publication

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.
PRIDEiP02746.

PTM databases

PhosphoSiteiP02746.

Expressioni

Gene expression databases

BgeeiP02746.
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. 14 interactions.
IntActiP02746. 7 interactions.
MINTiMINT-6629999.
STRINGi9606.ENSP00000313967.

Structurei

Secondary structure

1
253
Legend: HelixTurnBeta strand
Show more details
Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Beta strandi123 – 1275Combined sources
Beta strandi144 – 1496Combined sources
Turni155 – 1573Combined sources
Beta strandi159 – 1613Combined sources
Beta strandi166 – 17813Combined sources
Beta strandi180 – 19011Combined sources
Beta strandi192 – 1998Combined sources
Beta strandi202 – 2043Combined sources
Beta strandi206 – 21611Combined sources
Beta strandi221 – 23010Combined sources
Beta strandi241 – 2499Combined sources

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
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[»]
ProteinModelPortaliP02746.
SMRiP02746. Positions 119-250.
ModBaseiSearch...
MobiDBiSearch...

Miscellaneous databases

EvolutionaryTraceiP02746.

Family & Domainsi

Domains and Repeats

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Domaini37 – 8650Collagen-like 1Add
BLAST
Domaini60 – 11455Collagen-like 2Add
BLAST
Domaini117 – 253137C1qPROSITE-ProRule annotationAdd
BLAST

Sequence similaritiesi

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

Keywords - Domaini

Collagen, Repeat, Signal

Phylogenomic databases

eggNOGiNOG115400.
GeneTreeiENSGT00760000118830.
HOGENOMiHOG000085653.
HOVERGENiHBG108220.
InParanoidiP02746.
KOiK03987.
OMAiNLMRGRE.
PhylomeDBiP02746.
TreeFamiTF329591.

Family and domain databases

Gene3Di2.60.120.40. 1 hit.
InterProiIPR001073. C1q.
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)LengthDescriptionGraphical viewFeature identifierActions
Sequence conflicti28 – 281Q → E AA sequence (PubMed:708376).Curated
Sequence conflicti85 – 851N → D AA sequence (PubMed:708376).Curated
Sequence conflicti100 – 1001G → P AA sequence (PubMed:708376).Curated
Sequence conflicti100 – 1001G → P AA sequence (PubMed:486087).Curated

Natural variant

Feature keyPosition(s)LengthDescriptionGraphical viewFeature identifierActions
Natural varianti42 – 421G → D in C1QD. 1 Publication
VAR_008541
Natural varianti123 – 1231A → T in a breast cancer sample; somatic mutation. 1 Publication
VAR_035551

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_011542059.1.
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_011542059.1.
UniGeneiHs.8986.

3D structure databases

Select the link destinations:
PDBei
RCSB PDBi
PDBji
Links Updated
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[»]
ProteinModelPortaliP02746.
SMRiP02746. Positions 119-250.
ModBaseiSearch...
MobiDBiSearch...

Protein-protein interaction databases

BioGridi107174. 14 interactions.
IntActiP02746. 7 interactions.
MINTiMINT-6629999.
STRINGi9606.ENSP00000313967.

Chemistry

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

PhosphoSiteiP02746.

Polymorphism and mutation databases

BioMutaiC1QB.
DMDMi298286922.

Proteomic databases

PaxDbiP02746.
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.
GeneCardsiGC01P022979.
HGNCiHGNC:1242. C1QB.
HPAiHPA052116.
MIMi120570. gene.
613652. phenotype.
neXtProtiNX_P02746.
Orphaneti169147. Immunodeficiency due to an early component of complement deficiency.
PharmGKBiPA25623.
GenAtlasiSearch...

Phylogenomic databases

eggNOGiNOG115400.
GeneTreeiENSGT00760000118830.
HOGENOMiHOG000085653.
HOVERGENiHBG108220.
InParanoidiP02746.
KOiK03987.
OMAiNLMRGRE.
PhylomeDBiP02746.
TreeFamiTF329591.

Enzyme and pathway databases

ReactomeiREACT_7956. Classical antibody-mediated complement activation.
REACT_8024. Initial triggering of complement.

Miscellaneous databases

ChiTaRSiC1QB. human.
EvolutionaryTraceiP02746.
GenomeRNAii713.
NextBioi2898.
PROiP02746.
SOURCEiSearch...

Gene expression databases

BgeeiP02746.
CleanExiHS_C1QB.
ExpressionAtlasiP02746. baseline and differential.
GenevisibleiP02746. HS.

Family and domain databases

Gene3Di2.60.120.40. 1 hit.
InterProiIPR001073. C1q.
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...

Publicationsi

« Hide 'large scale' publications
  1. "The DNA sequence and biological annotation of human chromosome 1."
    Gregory S.G., Barlow K.F., McLay K.E., Kaul R., Swarbreck D., Dunham A., Scott C.E., Howe K.L., Woodfine K., Spencer C.C.A., Jones M.C., Gillson C., Searle S., Zhou Y., Kokocinski F., McDonald L., Evans R., Phillips K.
    , Atkinson A., Cooper R., Jones C., Hall R.E., Andrews T.D., Lloyd C., Ainscough R., Almeida J.P., Ambrose K.D., Anderson F., Andrew R.W., Ashwell R.I.S., Aubin K., Babbage A.K., Bagguley C.L., Bailey J., Beasley H., Bethel G., Bird C.P., Bray-Allen S., Brown J.Y., Brown A.J., Buckley D., Burton J., Bye J., Carder C., Chapman J.C., Clark S.Y., Clarke G., Clee C., Cobley V., Collier R.E., Corby N., Coville G.J., Davies J., Deadman R., Dunn M., Earthrowl M., Ellington A.G., Errington H., Frankish A., Frankland J., French L., Garner P., Garnett J., Gay L., Ghori M.R.J., Gibson R., Gilby L.M., Gillett W., Glithero R.J., Grafham D.V., Griffiths C., Griffiths-Jones S., Grocock R., Hammond S., Harrison E.S.I., Hart E., Haugen E., Heath P.D., Holmes S., Holt K., Howden P.J., Hunt A.R., Hunt S.E., Hunter G., Isherwood J., James R., Johnson C., Johnson D., Joy A., Kay M., Kershaw J.K., Kibukawa M., Kimberley A.M., King A., Knights A.J., Lad H., Laird G., Lawlor S., Leongamornlert D.A., Lloyd D.M., Loveland J., Lovell J., Lush M.J., Lyne R., Martin S., Mashreghi-Mohammadi M., Matthews L., Matthews N.S.W., McLaren S., Milne S., Mistry S., Moore M.J.F., Nickerson T., O'Dell C.N., Oliver K., Palmeiri A., Palmer S.A., Parker A., Patel D., Pearce A.V., Peck A.I., Pelan S., Phelps K., Phillimore B.J., Plumb R., Rajan J., Raymond C., Rouse G., Saenphimmachak C., Sehra H.K., Sheridan E., Shownkeen R., Sims S., Skuce C.D., Smith M., Steward C., Subramanian S., Sycamore N., Tracey A., Tromans A., Van Helmond Z., Wall M., Wallis J.M., White S., Whitehead S.L., Wilkinson J.E., Willey D.L., Williams H., Wilming L., Wray P.W., Wu Z., Coulson A., Vaudin M., Sulston J.E., Durbin R.M., Hubbard T., Wooster R., Dunham I., Carter N.P., McVean G., Ross M.T., Harrow J., Olson M.V., Beck S., Rogers J., Bentley D.R.
    Nature 441:315-321(2006) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
  2. "The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC)."
    The MGC Project Team
    Genome Res. 14:2121-2127(2004) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].
    Tissue: Brain.
  3. "Molecular cloning and characterization of the complementary DNA and gene coding for the B-chain of subcomponent C1q of the human complement system."
    Reid K.B.M.
    Biochem. J. 231:729-735(1985) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [MRNA] OF 26-253.
  4. "Amino acid sequence of the N-terminal 108 amino acid residues of the B chain of subcomponent C1q of the first component of human complement."
    Reid K.B.M., Thompson E.O.P.
    Biochem. J. 173:863-868(1978) [PubMed] [Europe PMC] [Abstract]
    Cited for: PROTEIN SEQUENCE OF 28-195, GLYCOSYLATION, PYROGLUTAMATE FORMATION AT GLU-28, DISULFIDE BOND, HYDROXYLATION.
  5. "Complete amino acid sequences of the three collagen-like regions present in subcomponent C1q of the first component of human complement."
    Reid K.B.M.
    Biochem. J. 179:367-371(1979) [PubMed] [Europe PMC] [Abstract]
    Cited for: PROTEIN SEQUENCE OF 28-135, HYDROXYLATION AT PRO-35; PRO-38; PRO-41; PRO-53; PRO-56; LYS-59; LYS-62; PRO-65; LYS-77; PRO-83; PRO-86; LYS-92; LYS-98; PRO-101; PRO-104; PRO-107 AND LYS-110.
  6. "Completion of the amino acid sequences of the A and B chains of subcomponent C1q of the first component of human complement."
    Reid K.B.M., Gagnon J., Frampton J.
    Biochem. J. 203:559-569(1982) [PubMed] [Europe PMC] [Abstract]
    Cited for: PROTEIN SEQUENCE OF 136-253.
  7. "Cloning and characterization of the complementary DNA for the B chain of normal human serum C1q."
    Reid K.B.M., Bentley D.R., Wood K.J.
    Philos. Trans. R. Soc. Lond., B, Biol. Sci. 306:345-354(1984) [PubMed] [Europe PMC] [Abstract]
    Cited for: NUCLEOTIDE SEQUENCE [MRNA] OF 226-253.
    Tissue: Liver.
  8. "Comparable content of hydroxylysine-linked glycosides in subcomponents C1q of the first component of human, bovine and mouse complement."
    Yonemasu K., Shinkai H., Sasaki T.
    Coll. Relat. Res. 1:385-390(1981) [PubMed] [Europe PMC] [Abstract]
    Cited for: GLYCOSYLATION ON HYDROXYLYSINES.
  9. "The crystal structure of the globular head of complement protein C1q provides a basis for its versatile recognition properties."
    Gaboriaud C., Juanhuix J., Gruez A., Lacroix M., Darnault C., Pignol D., Verger D., Fontecilla-Camps J.-C., Arlaud G.J.
    J. Biol. Chem. 278:46974-46982(2003) [PubMed] [Europe PMC] [Abstract]
    Cited for: X-RAY CRYSTALLOGRAPHY (1.85 ANGSTROMS) OF 119-250.
  10. "Molecular basis of hereditary C1q deficiency."
    Petry F.
    Immunobiology 199:286-294(1998) [PubMed] [Europe PMC] [Abstract]
    Cited for: REVIEW ON C1Q DEFICIENCY.
  11. "Molecular basis of a new type of C1q-deficiency associated with a non-functional low molecular weight (LMW) C1q: parallels and differences to other known genetic C1q-defects."
    Petry F., Hauptmann G., Goetz J., Grosshans E., Loos M.
    Immunopharmacology 38:189-201(1997) [PubMed] [Europe PMC] [Abstract]
    Cited for: VARIANT C1QD ASP-42.
  12. Cited for: VARIANT [LARGE SCALE ANALYSIS] THR-123.

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: July 22, 2015
This is version 171 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

External Data

Dasty 3

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 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.