InnateDB: Systems Biology of the Innate Immune Response

Homo sapiens Protein: C1QBP

Summary

InnateDB Protein

IDBP-21499.5

Last Modified

2014-10-13 [Report errors or provide feedback]

Gene Symbol

C1QBP

Protein Name

complement component 1, q subcomponent binding protein

Synonyms

gC1Q-R; GC1QBP; gC1qR; HABP1; p32; SF2p32;

Species

Homo sapiens

Ensembl Protein

ENSP00000225698

InnateDB Gene

IDBG-21497 (C1QBP)

Protein Structure

UniProt Annotation

Function

Is believed to be a multifunctional and multicompartmental protein involved in inflammation and infection processes, ribosome biogenesis, regulation of apoptosis, transcriptional regulation and pre-mRNA splicing. At the cell surface is thought to act as an endothelial receptor for plasma proteins of the complement and kallikrein-kinin cascades. Putative receptor for C1q; specifically binds to the globular "heads" of C1q thus inhibiting C1; may perform the receptor function through a complex with C1qR/CD93. In complex with cytokeratin-1/KRT1 is a high affinity receptor for kininogen-1/HMWK. Can also bind other plasma proteins, such as coagulation factor XII leading to its autoactivation. May function to bind initially fluid kininogen-1 to the cell membrane. The secreted form may enhance both extrinsic and intrinsic coagulation pathways. It is postulated that the cell surface form requires docking with transmembrane proteins for downstream signaling which might be specific for a cell-type or response. By acting as C1q receptor is involved in chemotaxis of immature dendritic cells and neutrophils and is proposed to signal through CD209/DC-SIGN on immature dendritic cells, through integrin alpha-4/beta-1 during trophoblast invasion of the decidua, and through integrin beta-1 during endothelial cell adhesion and spreading. Signaling involved in inhibition of innate immune response is implicating the PI3K-AKT/PKB pathway. In mitochondrial translation may be involved in formation of functional 55S mitoribosomes; the function seems to involve its RNA-binding activity. May be involved in the nucleolar ribosome maturation process; the function may involve the exchange of FBL for RRP1 in the association with pre-ribosome particles. Involved in regulation of RNA splicing by inhibiting the RNA-binding capacity of SRSF1 and its phosphorylation. Is required for the nuclear translocation of splicing factor U2AF1L4. Involved in regulation of CDKN2A- and HRK-mediated apoptosis. Stabilizes mitochondrial CDKN2A isoform smARF. May be involved in regulation of FOXC1 transcriptional activity and NFY/CCAAT-binding factor complex-mediated transcription. In infection processes acts as an attachment site for microbial proteins, including Listeria monocytogenes internalin B and Staphylococcus aureus protein A. May play a role in antibacterial defense as it can bind to cell surface hyaluronan and inhibit Streptococcus pneumoniae hyaluronate lyase. Involved in replication of Rubella virus. May be involved in modulation of the immune response; ligation by HCV core protein is resulting in suppresion of interleukin-12 production in monocyte-derived dendritic cells. Involved in regulation of antiviral response by inhibiting DDX58- and IFIH1- mediated signaling pathways probably involving its association with MAVS after viral infection. Involved in HIV-1 replication, presumably by contributing to splicing of viral RNA. {ECO:0000269PubMed:10022843, ECO:0000269PubMed:10479529, ECO:0000269PubMed:10722602, ECO:0000269PubMed:10747014, ECO:0000269PubMed:11086025, ECO:0000269PubMed:11859136, ECO:0000269PubMed:12833064, ECO:0000269PubMed:15243141, ECO:0000269PubMed:16140380, ECO:0000269PubMed:16177118, ECO:0000269PubMed:17881511, ECO:0000269PubMed:18676636, ECO:0000269PubMed:19004836, ECO:0000269PubMed:19164550, ECO:0000269PubMed:20810993, ECO:0000269PubMed:21536856, ECO:0000269PubMed:21544310, ECO:0000269PubMed:22700724, ECO:0000269PubMed:8662673, ECO:0000269PubMed:8710908, ECO:0000269PubMed:9461517}.

Subcellular Localization

Mitochondrion matrix. Nucleus. Cell membrane; Peripheral membrane protein; Extracellular side. Secreted. Cytoplasm. Nucleus, nucleolus. Note=Seems to be predominantly localized to mitochondria. Secreted by activated lymphocytes.

Disease Associations

Tissue Specificity

Expressed on cell surface of peripheral blood cells (at protein level); Surface expression is reported for macrophages and monocyte-derived dendritic cells. {ECO:0000269PubMed:12574814, ECO:0000269PubMed:8662673}.

Comments

Interactions

Number of Interactions

This gene and/or its encoded proteins are associated with 164 experimentally validated interaction(s) in this database.
They are also associated with 1 interaction(s) predicted by orthology.

Experimentally validated
Total	164 [view]
Protein-Protein	164 [view]
Protein-DNA	0
Protein-RNA	0
DNA-DNA	0
RNA-RNA	0
DNA-RNA	0

Predicted by orthology
Total	1 [view]

Gene Ontology

Molecular Function

Accession	GO Term
GO:0001849	complement component C1q binding
GO:0003714	transcription corepressor activity
GO:0003729	mRNA binding
GO:0005080	protein kinase C binding
GO:0005515	protein binding
GO:0005540	hyaluronic acid binding
GO:0008134	transcription factor binding
GO:0030984	kininogen binding
GO:0031690	adrenergic receptor binding
GO:0097177	mitochondrial ribosome binding

Biological Process

GO:0000122	negative regulation of transcription from RNA polymerase II promoter
GO:0006351	transcription, DNA-templated
GO:0006397	mRNA processing
GO:0006915	apoptotic process
GO:0006955	immune response
GO:0006958	complement activation, classical pathway
GO:0007596	blood coagulation
GO:0007597	blood coagulation, intrinsic pathway
GO:0008380	RNA splicing
GO:0014065	phosphatidylinositol 3-kinase signaling
GO:0016032	viral process
GO:0030449	regulation of complement activation
GO:0032689	negative regulation of interferon-gamma production
GO:0032695	negative regulation of interleukin-12 production
GO:0039534	negative regulation of MDA-5 signaling pathway
GO:0039536	negative regulation of RIG-I signaling pathway
GO:0042256	mature ribosome assembly
GO:0043065	positive regulation of apoptotic process
GO:0045087	innate immune response (InnateDB)
GO:0045785	positive regulation of cell adhesion
GO:0048025	negative regulation of mRNA splicing, via spliceosome
GO:0050687	negative regulation of defense response to virus
GO:0051897	positive regulation of protein kinase B signaling
GO:0070131	positive regulation of mitochondrial translation
GO:0090023	positive regulation of neutrophil chemotaxis
GO:1900026	positive regulation of substrate adhesion-dependent cell spreading
GO:1901165	positive regulation of trophoblast cell migration
GO:2000510	positive regulation of dendritic cell chemotaxis

Cellular Component

GO:0005615	extracellular space
GO:0005634	nucleus
GO:0005730	nucleolus
GO:0005737	cytoplasm
GO:0005739	mitochondrion
GO:0005759	mitochondrial matrix
GO:0005829	cytosol
GO:0005886	plasma membrane
GO:0009986	cell surface
GO:0016020	membrane