Skip Header

You are using a version of browser that may not display all the features of this website. Please consider upgrading your browser.
The new UniProt website is here! Take me to UniProt BETA

UniProtKB - P02745 (C1QA_HUMAN)

Entry version 222 (25 May 2022)
Sequence version 2 (01 Jul 1993)
Previous versions | rss
Add a publicationFeedback
Protein

Complement C1q subcomponent subunit A

Gene

C1QA

Organism
Homo sapiens (Human)
Status
Reviewed-Annotation score:

Annotation score:5 out of 5

<p>The annotation score provides a heuristic measure of the annotation content of a UniProtKB entry or proteome. This score <strong>cannot</strong> be used as a measure of the accuracy of the annotation as we cannot define the 'correct annotation' for any given protein.<p><a href='/help/annotation_score' target='_top'>More...</a></p>-Experimental evidence at protein leveli <p>This indicates the type of evidence that supports the existence of the protein. Note that the 'protein existence' evidence does not give information on the accuracy or correctness of the sequence(s) displayed.<p><a href='/help/protein_existence' target='_top'>More...</a></p>

<p>This section provides any useful information about the protein, mostly biological knowledge.<p><a href='/help/function_section' target='_top'>More...</a></p>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.

<p>The <a href="http://www.geneontology.org/">Gene Ontology (GO)</a> project provides a set of hierarchical controlled vocabulary split into 3 categories:<p><a href='/help/gene_ontology' target='_top'>More...</a></p>GO - Molecular functioni

  • amyloid-beta binding Source: ARUK-UCL
Complete GO annotation on QuickGO ...

GO - Biological processi

Complete GO annotation on QuickGO ...

<p>UniProtKB Keywords constitute a <a href="http://www.uniprot.org/keywords">controlled vocabulary</a> with a hierarchical structure. Keywords summarise the content of a UniProtKB entry and facilitate the search for proteins of interest.<p><a href='/help/keywords' target='_top'>More...</a></p>Keywordsi

Biological processComplement pathway, Host-virus interaction, Immunity, Innate immunity

Enzyme and pathway databases

Pathway Commons web resource for biological pathway data

More...PathwayCommonsi		P02745

Reactome - a knowledgebase of biological pathways and processes

More...Reactomei		R-HSA-166663, Initial triggering of complement
R-HSA-173623, Classical antibody-mediated complement activation
R-HSA-977606, Regulation of Complement cascade

SignaLink: a signaling pathway resource with multi-layered regulatory networks

More...SignaLinki		P02745

SIGNOR Signaling Network Open Resource

More...SIGNORi		P02745

<p>This section provides information about the protein and gene name(s) and synonym(s) and about the organism that is the source of the protein sequence.<p><a href='/help/names_and_taxonomy_section' target='_top'>More...</a></p>Names & Taxonomyi

<p>This subsection of the <a href="http://www.uniprot.org/help/names%5Fand%5Ftaxonomy%5Fsection">Names and taxonomy</a> section provides an exhaustive list of all names of the protein, from commonly used to obsolete, to allow unambiguous identification of a protein.<p><a href='/help/protein_names' target='_top'>More...</a></p>Protein namesi
Recommended name:
Complement C1q subcomponent subunit A
<p>This subsection of the <a href="http://www.uniprot.org/help/names%5Fand%5Ftaxonomy%5Fsection">Names and taxonomy</a> section indicates the name(s) of the gene(s) that code for the protein sequence(s) described in the entry. Four distinct tokens exist: 'Name', 'Synonyms', 'Ordered locus names' and 'ORF names'.<p><a href='/help/gene_name' target='_top'>More...</a></p>Gene namesi
Name:C1QA
<p>This subsection of the <a href="http://www.uniprot.org/help/names%5Fand%5Ftaxonomy%5Fsection">Names and taxonomy</a> section provides information on the name(s) of the organism that is the source of the protein sequence.<p><a href='/help/organism-name' target='_top'>More...</a></p>OrganismiHomo sapiens (Human)
<p>This subsection of the <a href="http://www.uniprot.org/help/names%5Fand%5Ftaxonomy%5Fsection">Names and taxonomy</a> section shows the unique identifier assigned by the NCBI to the source organism of the protein. This is known as the 'taxonomic identifier' or 'taxid'.<p><a href='/help/taxonomic_identifier' target='_top'>More...</a></p>Taxonomic identifieri9606 [NCBI]
<p>This subsection of the <a href="http://www.uniprot.org/help/names%5Fand%5Ftaxonomy%5Fsection">Names and taxonomy</a> section contains the taxonomic hierarchical classification lineage of the source organism. It lists the nodes as they appear top-down in the taxonomic tree, with the more general grouping listed first.<p><a href='/help/taxonomic_lineage' target='_top'>More...</a></p>Taxonomic lineageiEukaryota › Metazoa › Chordata › Craniata › Vertebrata › Euteleostomi › Mammalia › Eutheria › Euarchontoglires › Primates › Haplorrhini › Catarrhini › Hominidae › Homo
<p>This subsection of the <a href="http://www.uniprot.org/help/names%5Fand%5Ftaxonomy%5Fsection">Names and taxonomy</a> section is present for entries that are part of a <a href="http://www.uniprot.org/proteomes">proteome</a>, i.e. of a set of proteins thought to be expressed by organisms whose genomes have been completely sequenced.<p><a href='/help/proteomes_manual' target='_top'>More...</a></p>Proteomesi
  • UP000005640 <p>A UniProt <a href="http://www.uniprot.org/manual/proteomes%5Fmanual">proteome</a> can consist of several components.<br></br>The component name refers to the genomic component encoding a set of proteins.<p><a href='/help/proteome_component' target='_top'>More...</a></p> Componenti: Chromosome 1

Organism-specific databases

Human Gene Nomenclature Database

More...HGNCi		HGNC:1241, C1QA

Online Mendelian Inheritance in Man (OMIM)

More...MIMi		120550, gene

neXtProt; the human protein knowledge platform

More...neXtProti		NX_P02745

Eukaryotic Pathogen, Vector and Host Database Resources

More...VEuPathDBi		HostDB:ENSG00000173372

<p>This section provides information on the location and the topology of the mature protein in the cell.<p><a href='/help/subcellular_location_section' target='_top'>More...</a></p>Subcellular locationi

Keywords - Cellular componenti

Secreted

<p>This section provides information on the disease(s) and phenotype(s) associated with a protein.<p><a href='/help/pathology_and_biotech_section' target='_top'>More...</a></p>Pathology & Biotechi

<p>This subsection of the 'Pathology and Biotech' section provides information on the disease(s) associated with genetic variations in a given protein. The information is extracted from the scientific literature and diseases that are also described in the <a href="http://www.ncbi.nlm.nih.gov/sites/entrez?db=omim">OMIM</a> database are represented with a <a href="http://www.uniprot.org/diseases">controlled vocabulary</a> in the following way:<p><a href='/help/involvement_in_disease' target='_top'>More...</a></p>Involvement in diseasei

Complement component C1q deficiency (C1QD)
The disease is caused by variants 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.
Related information in OMIM

Organism-specific databases

DisGeNET

More...DisGeNETi		712

MalaCards human disease database

More...MalaCardsi		C1QA
MIMi613652, phenotype

Open Targets

More...OpenTargetsi		ENSG00000173372

Orphanet; a database dedicated to information on rare diseases and orphan drugs

More...Orphaneti		300345, Autosomal systemic lupus erythematosus
169147, Immunodeficiency due to a classical component pathway complement deficiency

The Pharmacogenetics and Pharmacogenomics Knowledge Base

More...PharmGKBi		PA25622

Miscellaneous databases

Pharos NIH Druggable Genome Knowledgebase

More...Pharosi		P02745, Tbio

Chemistry databases

Drug and drug target database

More...DrugBanki		DB00112, Bevacizumab
DB00002, Cetuximab
DB00111, Daclizumab
DB00005, Etanercept
DB00110, Palivizumab

Genetic variation databases

BioMuta curated single-nucleotide variation and disease association database

More...BioMutai		C1QA

Domain mapping of disease mutations (DMDM)

More...DMDMi		399138

<p>This section describes post-translational modifications (PTMs) and/or processing events.<p><a href='/help/ptm_processing_section' target='_top'>More...</a></p>PTM / Processingi

Molecule processing

Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the 'PTM / Processing' section denotes the presence of an N-terminal signal peptide.<p><a href='/help/signal' target='_top'>More...</a></p>Signal peptidei1 – 221 PublicationAdd BLAST22
<p>This subsection of the 'PTM / Processing' section describes the extent of a polypeptide chain in the mature protein following processing or proteolytic cleavage.<p><a href='/help/chain' target='_top'>More...</a></p>ChainiPRO_000000351723 – 245Complement C1q subcomponent subunit AAdd BLAST223

Amino acid modifications

Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the PTM / Processing":/help/ptm_processing_section section describes the positions of cysteine residues participating in disulfide bonds.<p><a href='/help/disulfid' target='_top'>More...</a></p>Disulfide bondi26Interchain (with C-29 in B chain)
<p>This subsection of the 'PTM / Processing' section specifies the position and type of each modified residue excluding <a href="http://www.uniprot.org/manual/lipid">lipids</a>, <a href="http://www.uniprot.org/manual/carbohyd">glycans</a> and <a href="http://www.uniprot.org/manual/crosslnk">protein cross-links</a>.<p><a href='/help/mod_res' target='_top'>More...</a></p>Modified residuei335-hydroxylysine1 Publication1
<p>This subsection of the <a href="http://www.uniprot.org/help/ptm%5Fprocessing%5Fsection">PTM / Processing</a> section specifies the position and type of each covalently attached glycan group (mono-, di-, or polysaccharide).<p><a href='/help/carbohyd' target='_top'>More...</a></p>Glycosylationi33O-linked (Gal...) hydroxylysine1 Publication1
Modified residuei394-hydroxyproline1 Publication1
Modified residuei454-hydroxyproline1 Publication1
Modified residuei485-hydroxylysine1 Publication1
Glycosylationi48O-linked (Gal...) hydroxylysine1 Publication1
Modified residuei544-hydroxyproline1 Publication1
Modified residuei574-hydroxyproline1 Publication1
Modified residuei675-hydroxylysine1 Publication1
Glycosylationi67O-linked (Gal...) hydroxylysine1 Publication1
Modified residuei734-hydroxyproline1 Publication1
Modified residuei794-hydroxyproline1 Publication1
Modified residuei854-hydroxyproline1 Publication1
Modified residuei1005-hydroxylysine1 Publication1
Glycosylationi100O-linked (Gal...) hydroxylysine1 Publication1
Glycosylationi146N-linked (GlcNAc...) asparagine2 Publications1

<p>This subsection of the <a href="http://www.uniprot.org/help/ptm%5Fprocessing%5Fsection">PTM/processing</a> section describes post-translational modifications (PTMs). This subsection <strong>complements</strong> the information provided at the sequence level or describes modifications for which <strong>position-specific data is not yet available</strong>.<p><a href='/help/post-translational_modification' target='_top'>More...</a></p>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

jPOST - Japan Proteome Standard Repository/Database

More...jPOSTi		P02745

MassIVE - Mass Spectrometry Interactive Virtual Environment

More...MassIVEi		P02745

PaxDb, a database of protein abundance averages across all three domains of life

More...PaxDbi		P02745

PeptideAtlas

More...PeptideAtlasi		P02745

PRoteomics IDEntifications database

More...PRIDEi		P02745

ProteomicsDB: a multi-organism proteome resource

More...ProteomicsDBi		51561

PTM databases

GlyConnect protein glycosylation platform

More...GlyConnecti		1142, 7 N-Linked glycans (1 site)

GlyGen: Computational and Informatics Resources for Glycoscience

More...GlyGeni		P02745, 5 sites, 11 N-linked glycans (1 site)

iPTMnet integrated resource for PTMs in systems biology context

More...iPTMneti		P02745

Comprehensive resource for the study of protein post-translational modifications (PTMs) in human, mouse and rat.

More...PhosphoSitePlusi		P02745

<p>This section provides information on the expression of a gene at the mRNA or protein level in cells or in tissues of multicellular organisms.<p><a href='/help/expression_section' target='_top'>More...</a></p>Expressioni

Gene expression databases

Bgee dataBase for Gene Expression Evolution

More...Bgeei		ENSG00000173372, Expressed in spleen and 224 other tissues

ExpressionAtlas, Differential and Baseline Expression

More...ExpressionAtlasi		P02745, baseline and differential

Genevisible search portal to normalized and curated expression data from Genevestigator

More...Genevisiblei		P02745, HS

Organism-specific databases

Human Protein Atlas

More...HPAi		ENSG00000173372, Tissue enhanced (lymphoid)

<p>This section provides information on the quaternary structure of a protein and on interaction(s) with other proteins or protein complexes.<p><a href='/help/interaction_section' target='_top'>More...</a></p>Interactioni

<p>This subsection of the <a href="http://www.uniprot.org/help/interaction%5Fsection">'Interaction'</a> section provides information about the protein quaternary structure and interaction(s) with other proteins or protein complexes (with the exception of physiological receptor-ligand interactions which are annotated in the <a href="http://www.uniprot.org/help/function%5Fsection">'Function'</a> section).<p><a href='/help/subunit_structure' target='_top'>More...</a></p>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.

Interacts (via C-terminus) with CD33; this interaction activates CD33 inhibitory motifs (PubMed:28325905).

Interacts with CR1 (via Sushi 24 and Sushi 25 domains) (PubMed:29563915, PubMed:9324355).

3 Publications

(Microbial infection) Interacts with Staphylococcus aureus protein Cna; this interaction results in the inhibition of the classical complement pathway.

1 Publication

<p>This subsection of the '<a href="http://www.uniprot.org/help/interaction%5Fsection">Interaction</a>' section provides information about binary protein-protein interactions. The data presented in this section are a quality-filtered subset of binary interactions automatically derived from the <a href="https://www.ebi.ac.uk/intact/">IntAct database</a>. It is updated at every <a href="http://www.uniprot.org/help/synchronization">UniProt release</a>.<p><a href='/help/binary_interactions' target='_top'>More...</a></p>Binary interactionsi

Hide details

Protein-protein interaction databases

The Biological General Repository for Interaction Datasets (BioGRID)

More...BioGRIDi		107173, 207 interactors

ComplexPortal: manually curated resource of macromolecular complexes

More...ComplexPortali		CPX-1919, Complement component C1q complex

CORUM comprehensive resource of mammalian protein complexes

More...CORUMi		P02745

Protein interaction database and analysis system

More...IntActi		P02745, 23 interactors

Molecular INTeraction database

More...MINTi		P02745

STRING: functional protein association networks

More...STRINGi		9606.ENSP00000363773

Miscellaneous databases

RNAct, Protein-RNA interaction predictions for model organisms.

More...RNActi		P02745, protein

<p>This section provides information on the tertiary and secondary structure of a protein.<p><a href='/help/structure_section' target='_top'>More...</a></p>Structurei

Secondary structure

1245
Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details

3D structure databases

AlphaFold Protein Structure Database

More...AlphaFoldDBi		P02745

Small Angle Scattering Biological Data Bank

More...SASBDBi		P02745

SWISS-MODEL Repository - a database of annotated 3D protein structure models

More...SMRi		P02745

Database of comparative protein structure models

More...ModBasei		Search...

Protein Data Bank in Europe - Knowledge Base

More...PDBe-KBi		Search...

Miscellaneous databases

Relative evolutionary importance of amino acids within a protein sequence

More...EvolutionaryTracei		P02745

<p>This section provides information on sequence similarities with other proteins and the domain(s) present in a protein.<p><a href='/help/family_and_domains_section' target='_top'>More...</a></p>Family & Domainsi

Domains and Repeats

Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the <a href="http://www.uniprot.org/help/family%5Fand%5Fdomains%5Fsection">Family and Domains</a> section describes the position and type of a domain, which is defined as a specific combination of secondary structures organized into a characteristic three-dimensional structure or fold.<p><a href='/help/domain' target='_top'>More...</a></p>Domaini31 – 109Collagen-likeAdd BLAST79
Domaini110 – 245C1qPROSITE-ProRule annotationAdd BLAST136

Region

Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the 'Family and Domains' section describes a region of interest that cannot be described in other subsections.<p><a href='/help/region' target='_top'>More...</a></p>Regioni27 – 114DisorderedSequence analysisAdd BLAST88

Compositional bias

Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the 'Family and Domains' section describes the position of regions of compositional bias within the protein and the particular type of amino acids that are over-represented within those regions.<p><a href='/help/compbias' target='_top'>More...</a></p>Compositional biasi27 – 48Basic and acidic residuesSequence analysisAdd BLAST22

Keywords - Domaini

Collagen, Repeat, Signal

Phylogenomic databases

evolutionary genealogy of genes: Non-supervised Orthologous Groups

More...eggNOGi		ENOG502RZM2, Eukaryota

Ensembl GeneTree

More...GeneTreei		ENSGT00940000162143

The HOGENOM Database of Homologous Genes from Fully Sequenced Organisms

More...HOGENOMi		CLU_001074_3_1_1

InParanoid: Eukaryotic Ortholog Groups

More...InParanoidi		P02745

Identification of Orthologs from Complete Genome Data

More...OMAi		DMVITNQ

Database of Orthologous Groups

More...OrthoDBi		1258047at2759

Database for complete collections of gene phylogenies

More...PhylomeDBi		P02745

TreeFam database of animal gene trees

More...TreeFami		TF329591

Family and domain databases

Gene3D Structural and Functional Annotation of Protein Families

More...Gene3Di		2.60.120.40, 1 hit

Integrated resource of protein families, domains and functional sites

More...InterProi		View protein in InterPro
IPR001073, C1q_dom
IPR008160, Collagen
IPR037572, Complement_C1q_A
IPR008983, Tumour_necrosis_fac-like_dom

The PANTHER Classification System

More...PANTHERi		PTHR15427:SF26, PTHR15427:SF26, 1 hit

Pfam protein domain database

More...Pfami		View protein in Pfam
PF00386, C1q, 1 hit
PF01391, Collagen, 1 hit

Protein Motif fingerprint database; a protein domain database

More...PRINTSi		PR00007, COMPLEMNTC1Q

Simple Modular Architecture Research Tool; a protein domain database

More...SMARTi		View protein in SMART
SM00110, C1Q, 1 hit

Superfamily database of structural and functional annotation

More...SUPFAMi		SSF49842, SSF49842, 1 hit

PROSITE; a protein domain and family database

More...PROSITEi		View protein in PROSITE
PS50871, C1Q, 1 hit

<p>This section displays by default the canonical protein sequence and upon request all isoforms described in the entry. It also includes information pertinent to the sequence(s), including <a href="http://www.uniprot.org/help/sequence%5Flength">length</a> and <a href="http://www.uniprot.org/help/sequences">molecular weight</a>. The information is filed in different subsections. The current subsections and their content are listed below:<p><a href='/help/sequences_section' target='_top'>More...</a></p>Sequence (1+)i

<p>This subsection of the <a href="http://www.uniprot.org/help/sequences%5Fsection">Sequence</a> section indicates if the <a href="http://www.uniprot.org/help/canonical%5Fand%5Fisoforms">canonical sequence</a> displayed by default in the entry is complete or not.<p><a href='/help/sequence_status' target='_top'>More...</a></p>Sequence statusi: Complete.

<p>This subsection of the <a href="http://www.uniprot.org/help/sequences%5Fsection">Sequence</a> section indicates if the <a href="http://www.uniprot.org/help/canonical%5Fand%5Fisoforms">canonical sequence</a> displayed by default in the entry is in its mature form or if it represents the precursor.<p><a href='/help/sequence_processing' target='_top'>More...</a></p>Sequence processingi: The displayed sequence is further processed into a mature form.

This entry has 1 described isoform and 1 potential isoform that is computationally mapped.Show allAlign All

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
<p>The checksum is a form of redundancy check that is calculated from the sequence. It is useful for tracking sequence updates.</p> <p>It should be noted that while, in theory, two different sequences could have the same checksum value, the likelihood that this would happen is extremely low.</p> <p>However UniProtKB may contain entries with identical sequences in case of multiple genes (paralogs).</p> <p>The checksum is computed as the sequence 64-bit Cyclic Redundancy Check value (CRC64) using the generator polynomial: x<sup>64</sup> + x<sup>4</sup> + x<sup>3</sup> + x + 1. The algorithm is described in the ISO 3309 standard. </p> <p class="publication">Press W.H., Flannery B.P., Teukolsky S.A. and Vetterling W.T.<br /> <strong>Cyclic redundancy and other checksums</strong><br /> <a href="http://www.nrbook.com/b/bookcpdf.php">Numerical recipes in C 2nd ed., pp896-902, Cambridge University Press (1993)</a>)</p> Checksum:i8FF6B6AE02D49C4C
GO

<p>In eukaryotic reference proteomes, unreviewed entries that are likely to belong to the same gene are computationally mapped, based on gene identifiers from Ensembl, EnsemblGenomes and model organism databases.<p><a href='/help/gene_centric_isoform_mapping' target='_top'>More...</a></p>Computationally mapped potential isoform sequencesi

There is 1 potential isoform mapped to this entry.BLASTAlignShow allAdd to basket
EntryEntry nameProtein names
Gene namesLengthAnnotation
X6RLJ0X6RLJ0_HUMAN
Complement C1q subcomponent subunit...
C1QA
220Annotation score:

Annotation score:2 out of 5

<p>The annotation score provides a heuristic measure of the annotation content of a UniProtKB entry or proteome. This score <strong>cannot</strong> be used as a measure of the accuracy of the annotation as we cannot define the 'correct annotation' for any given protein.<p><a href='/help/annotation_score' target='_top'>More...</a></p>

Experimental Info

Feature keyPosition(s)DescriptionActionsGraphical viewLength
<p>This subsection of the 'Sequence' section reports difference(s) between the canonical sequence (displayed by default in the entry) and the different sequence submissions merged in the entry. These various submissions may originate from different sequencing projects, different types of experiments, or different biological samples. Sequence conflicts are usually of unknown origin.<p><a href='/help/conflict' target='_top'>More...</a></p>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
<p>This subsection of the 'Sequence' section describes natural variant(s) of the protein sequence.<p><a href='/help/variant' target='_top'>More...</a></p>Natural variantiVAR_02109023E → K1 PublicationCorresponds to variant dbSNP:rs17887074EnsemblClinVar.1

Sequence databases

Select the link destinations:

EMBL nucleotide sequence database

More...EMBLi

GenBank nucleotide sequence database

More...GenBanki

DNA Data Bank of Japan; a nucleotide sequence database

More...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

The Consensus CDS (CCDS) project

More...CCDSi		CCDS226.1

Protein sequence database of the Protein Information Resource

More...PIRi		S14350, C1HUQA

NCBI Reference Sequences

More...RefSeqi		NP_001334394.1, NM_001347465.1
NP_001334395.1, NM_001347466.1
NP_057075.1, NM_015991.3

Genome annotation databases

Ensembl eukaryotic genome annotation project

More...Ensembli		ENST00000374642.8; ENSP00000363773.3; ENSG00000173372.17
ENST00000402322.1; ENSP00000385564.1; ENSG00000173372.17

Database of genes from NCBI RefSeq genomes

More...GeneIDi		712

KEGG: Kyoto Encyclopedia of Genes and Genomes

More...KEGGi		hsa:712

Matched Annotation from NCBI and EMBL-EBI (MANE) - Phase one

More...MANE-Selecti		ENST00000374642.8; ENSP00000363773.3; NM_015991.4; NP_057075.1

UCSC genome browser

More...UCSCi		uc001bfy.4, human

<p>This section provides links to proteins that are similar to the protein sequence(s) described in this entry at different levels of sequence identity thresholds (100%, 90% and 50%) based on their membership in UniProt Reference Clusters (<a href="http://www.uniprot.org/help/uniref">UniRef</a>).<p><a href='/help/similar_proteins_section' target='_top'>More...</a></p>Similar proteinsi

<p>This section is used to point to information related to entries and found in data collections other than UniProtKB.<p><a href='/help/cross_references_section' target='_top'>More...</a></p>Cross-referencesi

<p>This subsection of the <a href="http://www.uniprot.org/manual/cross%5Freferences%5Fsection">Cross-references</a> section provides links to various web resources that are relevant for a specific protein.<p><a href='/help/web_resource' target='_top'>More...</a></p>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_001334394.1, NM_001347465.1
NP_001334395.1, NM_001347466.1
NP_057075.1, NM_015991.3

3D structure databases

Select the link destinations:

Protein Data Bank Europe

More...PDBei

Protein Data Bank RCSB

More...RCSB PDBi

Protein Data Bank Japan

More...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[»]
6FCZelectron microscopy10.00A112-244[»]
6Z6VX-ray2.19A/D110-245[»]
AlphaFoldDBiP02745
SASBDBiP02745
SMRiP02745
ModBaseiSearch...
PDBe-KBiSearch...

Protein-protein interaction databases

BioGRIDi107173, 207 interactors
ComplexPortaliCPX-1919, Complement component C1q complex
CORUMiP02745
IntActiP02745, 23 interactors
MINTiP02745
STRINGi9606.ENSP00000363773

Chemistry databases

DrugBankiDB00112, Bevacizumab
DB00002, Cetuximab
DB00111, Daclizumab
DB00005, Etanercept
DB00110, Palivizumab

PTM databases

GlyConnecti1142, 7 N-Linked glycans (1 site)
GlyGeniP02745, 5 sites, 11 N-linked glycans (1 site)
iPTMnetiP02745
PhosphoSitePlusiP02745

Genetic variation databases

BioMutaiC1QA
DMDMi399138

Proteomic databases

jPOSTiP02745
MassIVEiP02745
PaxDbiP02745
PeptideAtlasiP02745
PRIDEiP02745
ProteomicsDBi51561

Protocols and materials databases

Antibodypedia a portal for validated antibodies

More...Antibodypediai		707, 430 antibodies from 35 providers

The DNASU plasmid repository

More...DNASUi		712

Genome annotation databases

EnsembliENST00000374642.8; ENSP00000363773.3; ENSG00000173372.17
ENST00000402322.1; ENSP00000385564.1; ENSG00000173372.17
GeneIDi712
KEGGihsa:712
MANE-SelectiENST00000374642.8; ENSP00000363773.3; NM_015991.4; NP_057075.1
UCSCiuc001bfy.4, human

Organism-specific databases

Comparative Toxicogenomics Database

More...CTDi		712
DisGeNETi712

GeneCards: human genes, protein and diseases

More...GeneCardsi		C1QA
HGNCiHGNC:1241, C1QA
HPAiENSG00000173372, Tissue enhanced (lymphoid)
MalaCardsiC1QA
MIMi120550, gene
613652, phenotype
neXtProtiNX_P02745
OpenTargetsiENSG00000173372
Orphaneti300345, Autosomal systemic lupus erythematosus
169147, Immunodeficiency due to a classical component pathway complement deficiency
PharmGKBiPA25622
VEuPathDBiHostDB:ENSG00000173372

GenAtlas: human gene database

More...GenAtlasi		Search...

Phylogenomic databases

eggNOGiENOG502RZM2, Eukaryota
GeneTreeiENSGT00940000162143
HOGENOMiCLU_001074_3_1_1
InParanoidiP02745
OMAiDMVITNQ
OrthoDBi1258047at2759
PhylomeDBiP02745
TreeFamiTF329591

Enzyme and pathway databases

PathwayCommonsiP02745
ReactomeiR-HSA-166663, Initial triggering of complement
R-HSA-173623, Classical antibody-mediated complement activation
R-HSA-977606, Regulation of Complement cascade
SignaLinkiP02745
SIGNORiP02745

Miscellaneous databases

BioGRID ORCS database of CRISPR phenotype screens

More...BioGRID-ORCSi		712, 10 hits in 1072 CRISPR screens

ChiTaRS: a database of human, mouse and fruit fly chimeric transcripts and RNA-sequencing data

More...ChiTaRSi		C1QA, human
EvolutionaryTraceiP02745

The Gene Wiki collection of pages on human genes and proteins

More...GeneWikii		C1QA

Database of phenotypes from RNA interference screens in Drosophila and Homo sapiens

More...GenomeRNAii		712
PharosiP02745, Tbio

Protein Ontology

More...PROi		PR:P02745
RNActiP02745, protein

The Stanford Online Universal Resource for Clones and ESTs

More...SOURCEi		Search...

Gene expression databases

BgeeiENSG00000173372, Expressed in spleen and 224 other tissues
ExpressionAtlasiP02745, baseline and differential
GenevisibleiP02745, HS

Family and domain databases

Gene3Di2.60.120.40, 1 hit
InterProiView protein in InterPro
IPR001073, C1q_dom
IPR008160, Collagen
IPR037572, Complement_C1q_A
IPR008983, Tumour_necrosis_fac-like_dom
PANTHERiPTHR15427:SF26, PTHR15427:SF26, 1 hit
PfamiView protein in Pfam
PF00386, C1q, 1 hit
PF01391, Collagen, 1 hit
PRINTSiPR00007, COMPLEMNTC1Q
SMARTiView protein in SMART
SM00110, C1Q, 1 hit
SUPFAMiSSF49842, SSF49842, 1 hit
PROSITEiView protein in PROSITE
PS50871, C1Q, 1 hit

MobiDB: a database of protein disorder and mobility annotations

More...MobiDBi		Search...

<p>This section provides general information on the entry.<p><a href='/help/entry_information_section' target='_top'>More...</a></p>Entry informationi

<p>This subsection of the 'Entry information' section provides a mnemonic identifier for a UniProtKB entry, but it is not a stable identifier. Each reviewed entry is assigned a unique entry name upon integration into UniProtKB/Swiss-Prot.<p><a href='/help/entry_name' target='_top'>More...</a></p>Entry nameiC1QA_HUMAN
<p>This subsection of the 'Entry information' section provides one or more accession number(s). These are stable identifiers and should be used to cite UniProtKB entries. Upon integration into UniProtKB, each entry is assigned a unique accession number, which is called 'Primary (citable) accession number'.<p><a href='/help/accession_numbers' target='_top'>More...</a></p>AccessioniPrimary (citable) accession number: P02745
Secondary accession number(s): B2R4X2, Q5T963
<p>This subsection of the 'Entry information' section shows the date of integration of the entry into UniProtKB, the date of the last sequence update and the date of the last annotation modification ('Last modified'). The version number for both the entry and the <a href="http://www.uniprot.org/help/canonical%5Fand%5Fisoforms">canonical sequence</a> are also displayed.<p><a href='/help/entry_history' target='_top'>More...</a></p>Entry historyiIntegrated into UniProtKB/Swiss-Prot: July 21, 1986
Last sequence update: July 1, 1993
Last modified: May 25, 2022
This is version 222 of the entry and version 2 of the sequence. See complete history.
<p>This subsection of the 'Entry information' section indicates whether the entry has been manually annotated and reviewed by UniProtKB curators or not, in other words, if the entry belongs to the Swiss-Prot section of UniProtKB (<strong>reviewed</strong>) or to the computer-annotated TrEMBL section (<strong>unreviewed</strong>).<p><a href='/help/entry_status' target='_top'>More...</a></p>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.

<p>This section contains any relevant information that doesn't fit in any other defined sections<p><a href='/help/miscellaneous_section' target='_top'>More...</a></p>Miscellaneousi

Keywords - Technical termi

3D-structure, 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 genetic variants
    List of human entries with genetic variants
  3. Human variants curated from literature reports
    Index of human variants curated from literature reports
  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
UniProt is an ELIXIR core data resource
Main funding by: National Institutes of Health

We'd like to inform you that we have updated our Privacy Notice to comply with Europe’s new General Data Protection Regulation (GDPR) that applies since 25 May 2018.

Do not show this banner again