C1QBP

Complement component 1 Q subcomponent-binding protein, mitochondrial is a protein that in humans is encoded by the C1QBP gene.^[5][6][7]

C1QBP
Available structures PDB Ortholog search: PDBe RCSB List of PDB id codes 1P32, 3RPX
Identifiers
Aliases	C1QBP, GHABP1, SF2p32, gC1Q-R, gC1qR, p32, complement component 1, q subcomponent binding protein, complement C1q binding protein, COXPD33, SF2AP32
External IDs	OMIM: 601269; MGI: 1194505; HomoloGene: 31023; GeneCards: C1QBP; OMA:C1QBP - orthologs
Gene location (Human) Chr. Chromosome 17 (human)[1] Band 17p13.2 Start 5,432,777 bp[1] End 5,448,830 bp[1]
Gene location (Mouse) Chr. Chromosome 11 (mouse)[2] Band 11 B4|11 43.21 cM Start 70,868,662 bp[2] End 70,873,852 bp[2]
RNA expression pattern Bgee Human Mouse (ortholog) Top expressed in mucosa of transverse colon right adrenal gland rectum right adrenal cortex left adrenal gland left adrenal cortex islet of Langerhans mucosa of esophagus anterior pituitary gastrocnemius muscle Top expressed in primitive streak endothelial cell of lymphatic vessel condyle Paneth cell hair follicle fossa fetal liver hematopoietic progenitor cell otic placode facial motor nucleus medial ganglionic eminence More reference expression data BioGPS More reference expression data
Gene ontology Molecular function transcription corepressor activity transcription factor binding protein binding hyaluronic acid binding kininogen binding mitochondrial ribosome binding mRNA binding protein kinase C binding complement component C1q complex binding adrenergic receptor binding translation activator activity Cellular component cytosol extracellular region cell surface mitochondrial matrix nucleolus cytoplasm membrane mitochondrion nucleus extracellular space plasma membrane presynaptic active zone presynapse glutamatergic synapse GABA-ergic synapse Biological process blood coagulation, intrinsic pathway positive regulation of mitochondrial translation negative regulation of interferon-gamma production positive regulation of protein kinase B signaling negative regulation of MDA-5 signaling pathway regulation of transcription, DNA-templated adaptive immune response ribosome biogenesis negative regulation of defense response to virus immune system process mRNA processing negative regulation of transcription by RNA polymerase II transcription, DNA-templated positive regulation of trophoblast cell migration positive regulation of substrate adhesion-dependent cell spreading mature ribosome assembly negative regulation of mRNA splicing, via spliceosome immune response RNA splicing positive regulation of neutrophil chemotaxis complement activation, classical pathway positive regulation of apoptotic process phosphatidylinositol 3-kinase signaling innate immune response viral process positive regulation of dendritic cell chemotaxis regulation of complement activation negative regulation of RIG-I signaling pathway positive regulation of cell adhesion negative regulation of interleukin-12 production apoptotic process Sources:Amigo / QuickGO
Orthologs Species Human Mouse Entrez 708 12261 Ensembl ENSG00000108561 ENSMUSG00000018446 UniProt Q07021 O35658 Q8R5L1 RefSeq (mRNA) NM_001212 NM_007573 RefSeq (protein) NP_001203 NP_031599 Location (UCSC) Chr 17: 5.43 – 5.45 Mb Chr 11: 70.87 – 70.87 Mb PubMed search [3] [4]
Wikidata
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The human complement subcomponent C1q associates with C1r and C1s in order to yield the first component of the serum complement system. The protein encoded by this gene is known to bind to the globular heads of C1q molecules and inhibit C1 activation. This protein has also been identified as the p32 subunit of pre-mRNA splicing factor SF2, as well as a hyaluronic acid-binding protein.^[7]

Protein subunit

C1QBP is 282 amino acid in length and has three homologous subunit with its N-terminal 73 amino acid residues cleaved off to produce mature C1QBP. C1QBP appears as a monomer around 33 kDa on SDS-PAGE gel under both reducing and nonreducing condition but migrates as a trimer on size-exclusion chromatography (gel filtration).^[8]

Protein structure

The crystal structure of C1QBP at 2.25 Å resolution shows a homotrimeric ring displaying symmetry. The individual subunits are held together by noncovalent interactions and forms a doughnut shaped quaternary structure with a central cavity of 20 Å in diameter. Each Subunit of C1QBP has seven β-strand (β1- β7) and three α-helices (α1- α3). C1QBP is negatively charged on its soluble face while the membrane face is predominantly positively charged.^[9]

Interactions

C1QBP has been shown to interact with Protein kinase D1,^[10] BAT2,^[11] PRKCD,^[10] PKC alpha^[10] and Protein kinase Mζ.^[10] Other interacting partners of C1QBP include protein domains from pathogens such as bacteria,^[12] virus ^[13] and plasmodium falciparum.^[14] Plasma proteins including fibrinogen, FXII and HK have been demonstrated to interact with C1QBP in a zinc dependent manner,.^[15][16] Recently, a tumour homing peptide, LyP-1(CGNKRTRGC) has been shown to selectively bind to C1QBP in tumour expressing cells.^[17]