C1QBP - Complement component 1 Q subcomponent-binding protein, mitochondrial - human protein (Function)
 
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C1QBP »  Complement component 1 Q subcomponent-binding protein, mitochondrial
 
Protein also known as:  Mitochondrial matrix protein p32.
Gene name:  C1QBP
Family name: MAM33
Entry whose protein(s) existence is based on evidence at protein level
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1 101 1
GENE REF ISO

Function

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Overview 
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.  
21
  • CuratedUniProtKB
According to TCDB this is a transporter from family:
the putative ca(2+) uniporter (gc1qr) family  9.B.103.1.1  
GO molecular function 
Adrenergic receptor bindingdefinition[GO:0031690]  
  • ISSOrtholog Curator
Complement component C1q bindingdefinition[GO:0001849]  
1
  • IDAUniProtKB
Hyaluronic acid bindingdefinition[GO:0005540]  
1
  • IDAUniProtKB
Kininogen bindingdefinition[GO:0030984]  
1
  • IDAUniProtKB
Mitochondrial ribosome bindingdefinition[GO:0097177]  
  • ISSOrtholog Curator
mRNA bindingdefinition[GO:0003729]  
  • ISSOrtholog Curator
Protein bindingdefinition[GO:0005515]  
11
  • IPIIntAct
Protein kinase C bindingdefinition[GO:0005080] silver  
  • IEAOrtholog Compara
Transcription corepressor activitydefinition[GO:0003714]  
1
  • IDAUniProtKB
Transcription factor bindingdefinition[GO:0008134]  
1
  • IDAUniProtKB
GO biological process 
Apoptotic processdefinition[GO:0006915]  
  • IEAUniProtKB KW
Complement activation, classical pathwaydefinition[GO:0006958]  
  • IEAUniProtKB KW
Immune responsedefinition[GO:0006955]  
1
  • TASPINC
Innate immune responsedefinition[GO:0045087]  
  • IEAUniProtKB KW
Mature ribosome assemblydefinition[GO:0042256]  
1
  • IMPUniProtKB
mRNA processingdefinition[GO:0006397]  
  • IEAUniProtKB KW
Negative regulation of defense response to virusdefinition[GO:0050687]  
1
  • IMPUniProtKB
Negative regulation of interferon-gamma productiondefinition[GO:0032689]  
1
  • IDAUniProtKB
Negative regulation of interleukin-12 productiondefinition[GO:0032695]  
2
  • IDAUniProtKB
Negative regulation of MDA-5 signaling pathwaydefinition[GO:0039534]  
1
  • IDAUniProtKB
Negative regulation of mRNA splicing, via spliceosomedefinition[GO:0048025]  
1
  • IDAUniProtKB
Negative regulation of RIG-I signaling pathwaydefinition[GO:0039536]  
1
  • IDAUniProtKB
Negative regulation of transcription from RNA polymerase II promoterdefinition[GO:0000122]  
1
  • IDAUniProtKB
Phosphatidylinositol 3-kinase signalingdefinition[GO:0014065]  
1
  • IMPUniProtKB
Positive regulation of apoptotic processdefinition[GO:0043065]  
1
  • IMPUniProtKB
Positive regulation of cell adhesiondefinition[GO:0045785]  
1
  • IMPUniProtKB
Positive regulation of dendritic cell chemotaxisdefinition[GO:2000510]  
1
  • IMPUniProtKB
Positive regulation of mitochondrial translationdefinition[GO:0070131]  
  • ISSOrtholog Curator
Positive regulation of neutrophil chemotaxisdefinition[GO:0090023]  
1
  • IDAUniProtKB
Positive regulation of protein kinase B signalingdefinition[GO:0051897]  
1
  • IMPUniProtKB
Positive regulation of substrate adhesion-dependent cell spreadingdefinition[GO:1900026]  
1
  • IMPUniProtKB
Positive regulation of trophoblast cell migrationdefinition[GO:1901165]  
1
  • IMPUniProtKB
Regulation of complement activationdefinition[GO:0030449]  
1
  • IDAUniProtKB
RNA splicingdefinition[GO:0008380]  
  • IEAUniProtKB KW
Transcription, DNA-templateddefinition[GO:0006351]  
  • IEAUniProtKB KW
Viral processdefinition[GO:0016032]  
  • IEAUniProtKB KW
Pathways 
According to KEGG, this protein belongs to the following pathway:
Herpes simplex infection  hsa05168+708  
According to Reactome, this protein belongs to the following pathway:
Hemostasis  REACT_604  
Caution 
The subcellular location has been matter of debate. After being reported to be exclusively localized to mitochondria, demonstrations of promiscuous associations and locations have been rather considered as artifactual due to the extremely acidic character and the use of different tagged versions of the protein (PubMed9305894, PubMed11493647). However, by now the location to multiple compartments linked to diverse functions is accepted. The N-termini of the surface and secreted forms are identical to the reported processed mitochonddrial form.  
2
  • CuratedUniProtKB
 

Keywords

Biological process 
Adaptive immunity  definition   [KW-1064]
Apoptosis  definition   [KW-0053]
Complement pathway  definition   [KW-0180]
Host-virus interaction  definition   [KW-0945]
Immunity  definition   [KW-0391]
Innate immunity  definition   [KW-0399]
Ribosome biogenesis  definition   [KW-0690]
Transcription  definition   [KW-0804]
Transcription regulation  definition   [KW-0805]
mRNA processing  definition   [KW-0507]
mRNA splicing  definition   [KW-0508]
Technical term 
Reference proteome  definition   [KW-1185]
 

Further external links

GeneWiki: C1QBP
GenomeRNAi: 708
PRO: PR:Q07021