{{Short description|Protein-coding gene in the species Homo sapiens}} {{Infobox_gene}} '''Complement component 1 Q subcomponent-binding protein, mitochondrial''' is a protein that in humans is encoded by the ''C1QBP'' gene.<ref name="pmid8567680">{{cite journal | vauthors = Deb TB, Datta K | title = Molecular cloning of human fibroblast hyaluronic acid-binding protein confirms its identity with P-32, a protein co-purified with splicing factor SF2. Hyaluronic acid-binding protein as P-32 protein, co-purified with splicing factor SF2 | journal = J Biol Chem | volume = 271 | issue = 4 | pages = 2206–12 |date=March 1996 | pmid = 8567680 | doi = 10.1074/jbc.271.4.2206| doi-access = free }}</ref><ref name="pmid8195709">{{cite journal | vauthors = Ghebrehiwet B, Lim BL, Peerschke EI, Willis AC, Reid KB | title = Isolation, cDNA cloning, and overexpression of a 33-kD cell surface glycoprotein that binds to the globular "heads" of C1q | journal = J Exp Med | volume = 179 | issue = 6 | pages = 1809–21 |date=June 1994 | pmid = 8195709 | pmc = 2191527 | doi =10.1084/jem.179.6.1809 }}</ref><ref name="entrez">{{cite web | title = Entrez Gene: C1QBP complement component 1, q subcomponent binding protein| url = https://www.ncbi.nlm.nih.gov/gene?Db=gene&Cmd=ShowDetailView&TermToSearch=708}}</ref>
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.<ref name="entrez"/>
==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).<ref>{{cite journal |last1=Jiang |first1=Jianzhong |title=rystal structure of human p32, a doughnut-shaped acidic mitochondrial matrix protein |journal=PNAS |date=1999 |volume=96 |issue=7 |pages=3572–3577 |pmid=10097078 |pmc=22335 |doi=10.1073/pnas.96.7.3572 |bibcode=1999PNAS...96.3572J |doi-access=free }}</ref>
==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.<ref>{{cite journal |last1=Jiang |first1=Jianzhong |title=rystal structure of human p32, a doughnut-shaped acidic mitochondrial matrix protein |journal=PNAS |date=1999 |volume=96 |issue=7 |pages=3572–3577 |pmid=10097078 |pmc=22335 |doi=10.1073/pnas.96.7.3572 |bibcode=1999PNAS...96.3572J |doi-access=free }}</ref>
==Interactions== C1QBP has been shown to interact with Protein kinase D1,<ref name=pmid10831594>{{cite journal |last=Storz |first=P |author2=Hausser A |author3=Link G |author4=Dedio J |author5=Ghebrehiwet B |author6=Pfizenmaier K |author7=Johannes F J |date=August 2000 |title=Protein kinase C [micro] is regulated by the multifunctional chaperon protein p32 |journal=J. Biol. Chem. |volume=275 |issue=32 |pages=24601–7 |location = UNITED STATES| issn = 0021-9258| pmid = 10831594 |doi = 10.1074/jbc.M002964200 |doi-access=free }}</ref> BAT2,<ref name=pmid14667819>{{cite journal |doi=10.1016/S0888-7543(03)00235-0 |last=Lehner |first=Ben |author2=Semple Jennifer I |author3=Brown Stephanie E |author4=Counsell Damian |author5=Campbell R Duncan |author6=Sanderson Christopher M |date=January 2004 |title=Analysis of a high-throughput yeast two-hybrid system and its use to predict the function of intracellular proteins encoded within the human MHC class III region |journal=Genomics |volume=83 |issue=1 |pages=153–67 |location = United States| issn = 0888-7543| pmid = 14667819 }}</ref> PRKCD,<ref name=pmid10831594/> PKC alpha<ref name=pmid10831594/> and Protein kinase Mζ.<ref name=pmid10831594/> Other interacting partners of C1QBP include protein domains from pathogens such as bacteria,<ref>{{cite journal |last1=Braun |first1=Laurence |last2=Ghebrehiwet |first2=Berhane |last3=Cossart |first3=Pascale |title=gC1q-R/p32, a C1q-binding protein, is a receptor for the InlB invasion protein of Listeria monocytogenes |journal=The EMBO Journal |date=2000 |volume=19 |issue=7 |pages=1458–1466 |pmid=10747014 |doi=10.1093/emboj/19.7.1458|pmc=310215 }}</ref> virus <ref>{{cite journal |last1=Kittlesen |first1=David J. |last2=Chianese-Bullock |first2=Kimberly A. |last3=Yao |first3=Zhi Q |last4=Braciale |first4=Thomas J. |last5=Hahn |first5=Young S. |title=Interaction between complement receptor gC1qR and hepatitis C virus core protein inhibits T-lymphocyte proliferation |journal=J Clin Invest |volume=106 |issue=10 |pages=1239–1249 |pmid=11086025 |pmc=381434 |doi=10.1172/jci10323|year=2000 }}</ref> and plasmodium falciparum.<ref>{{cite journal |last1=Magallón-Tejada |first1=Ariel |title=Cytoadhesion to gC1qR through Plasmodium falciparum Erythrocyte Membrane Protein 1 in Severe Malaria |journal=PLOS Pathog |date=2016 |volume=12 |issue=11 |article-number=e1006011 |pmid=27835682 |pmc=5106025 |doi=10.1371/journal.ppat.1006011 |doi-access=free }}</ref> Plasma proteins including fibrinogen, FXII and HK have been demonstrated to interact with C1QBP in a zinc dependent manner,.<ref>{{cite journal |last1=Pathak |first1=Monika |last2=Kaira |first2=Bubacarr G. |last3=Slater |first3=Alexandre |last4=Emsley |first4=Jonas |title=Cell Receptor and Cofactor Interactions of the Contact Activation System and Factor XI |journal=Frontiers in Medicine |date=2018 |volume=5 |page=66 |pmid=29619369 |pmc=5871670 |doi=10.3389/fmed.2018.00066|doi-access=free }}</ref><ref>{{cite journal |last1=Peerschke |first1=EI |last2=Bayer |first2=AS |last3=Ghebrehiwet |first3=B |last4=Xiong |first4=YQ |title=gC1qR/p33 blockade reduces Staphylococcus aureus colonization of target tissues in an animal model of infective endocarditis |journal=Infect Immun |date=2006 |volume=74 |issue=8 |pages=4418–4423 |pmid=16861627 |pmc=1539591 |doi=10.1128/iai.01794-05}}</ref> Recently, a tumour homing peptide, LyP-1(CGNKRTRGC) has been shown to selectively bind to C1QBP in tumour expressing cells.<ref>{{cite journal |last1=Paasonen |first1=Lauri |last2=Sharma |first2=Shweta |last3=Braun |first3=Gary B. |last4=Kotamraju |first4=Venkata R. |last5=Chung |first5=Thomas D.Y. |last6=She |first6=Zhigang |last7=Sugahara |first7=Kazuki N |last8=Yliperttula |first8=Marjo |last9=Wu |first9=Bainan |last10=Pellecchia |first10=Maurizio |last11=Ruoslahti |first11=Erkki |last12=Teesalu |first12=Tambet |title=New p32/gC1qR Ligands for Targeted Tumor Drug Delivery |journal=ChemBioChem |date=2017 |volume=17 |issue=7 |pages=570–575 |pmid=26895508 |pmc=5433940 |doi=10.1002/cbic.201500564}}</ref>
==References== {{reflist}}
==Further reading== {{refbegin | 2}} *{{cite journal | vauthors=Krainer AR, Mayeda A, Kozak D, Binns G |title=Functional expression of cloned human splicing factor SF2: homology to RNA-binding proteins, U1 70K, and Drosophila splicing regulators. |journal=Cell |volume=66 |issue= 2 |pages= 383–94 |year= 1991 |pmid= 1830244 |doi=10.1016/0092-8674(91)90627-B |s2cid=24119556 }} *{{cite journal | vauthors=Busby TF, Ingham KC |title=NH2-terminal calcium-binding domain of human complement C1s- mediates the interaction of C1r- with C1q. |journal=Biochemistry |volume=29 |issue= 19 |pages= 4613–8 |year= 1990 |pmid= 2372546 |doi=10.1021/bi00471a016 }} *{{cite journal | vauthors=Fridell RA, Harding LS, Bogerd HP, Cullen BR |title=Identification of a novel human zinc finger protein that specifically interacts with the activation domain of lentiviral Tat proteins. |journal=Virology |volume=209 |issue= 2 |pages= 347–57 |year= 1995 |pmid= 7778269 |doi= 10.1006/viro.1995.1266 |doi-access= free }} *{{cite journal | vauthors=Luo Y, Yu H, Peterlin BM |title=Cellular protein modulates effects of human immunodeficiency virus type 1 Rev. |journal=J. Virol. |volume=68 |issue= 6 |pages= 3850–6 |year= 1994 |pmid= 8189522 |doi= 10.1128/JVI.68.6.3850-3856.1994| pmc=236890 }} *{{cite journal | vauthors=Honoré B, Madsen P, Rasmussen HH |title=Cloning and expression of a cDNA covering the complete coding region of the P32 subunit of human pre-mRNA splicing factor SF2. |journal=Gene |volume=134 |issue= 2 |pages= 283–7 |year= 1994 |pmid= 8262387 |doi=10.1016/0378-1119(93)90108-F |display-authors=etal}} *{{cite journal | vauthors=Tange TO, Jensen TH, Kjems J |title=In vitro interaction between human immunodeficiency virus type 1 Rev protein and splicing factor ASF/SF2-associated protein, p32. |journal=J. Biol. Chem. |volume=271 |issue= 17 |pages= 10066–72 |year= 1996 |pmid= 8626563 |doi=10.1074/jbc.271.17.10066 |doi-access=free }} *{{cite journal | vauthors=Guo N, Weremowicz S, Lynch N |title=Assignment of C1QBP encoding the C1q globular domain binding protein (gC1q-R) to human chromosome 17 band p13.3 by in situ hybridization. |journal=Cytogenet. Cell Genet. |volume=77 |issue= 3–4 |pages= 283–4 |year= 1997 |pmid= 9284938 |doi=10.1159/000134598 |display-authors=etal}} *{{cite journal | vauthors=Majumdar M, Datta K |title=Assignment of cDNA encoding hyaluronic acid-binding protein 1 to human chromosome 17p12-p13. |journal=Genomics |volume=51 |issue= 3 |pages= 476–7 |year= 1998 |pmid= 9721222 |doi= 10.1006/geno.1998.5364 }} *{{cite journal | vauthors=Petersen-Mahrt SK, Estmer C, Ohrmalm C |title=The splicing factor-associated protein, p32, regulates RNA splicing by inhibiting ASF/SF2 RNA binding and phosphorylation. |journal=EMBO J. |volume=18 |issue= 4 |pages= 1014–24 |year= 1999 |pmid= 10022843 |doi= 10.1093/emboj/18.4.1014 | pmc=1171193 |display-authors=etal}} *{{cite journal | vauthors=Jiang J, Zhang Y, Krainer AR, Xu RM |title=Crystal structure of human p32, a doughnut-shaped acidic mitochondrial matrix protein. |journal=Proc. Natl. Acad. Sci. U.S.A. |volume=96 |issue= 7 |pages= 3572–7 |year= 1999 |pmid= 10097078 |doi=10.1073/pnas.96.7.3572 | pmc=22335 |bibcode=1999PNAS...96.3572J |doi-access=free }} *{{cite journal | vauthors=Braun L, Ghebrehiwet B, Cossart P |title=gC1q-R/p32, a C1q-binding protein, is a receptor for the InlB invasion protein of Listeria monocytogenes. |journal=EMBO J. |volume=19 |issue= 7 |pages= 1458–66 |year= 2000 |pmid= 10747014 |doi= 10.1093/emboj/19.7.1458 | pmc=310215 }} *{{cite journal | vauthors=Beatch MD, Hobman TC |title=Rubella virus capsid associates with host cell protein p32 and localizes to mitochondria. |journal=J. Virol. |volume=74 |issue= 12 |pages= 5569–76 |year= 2000 |pmid= 10823864 |doi=10.1128/JVI.74.12.5569-5576.2000 | pmc=112044 }} *{{cite journal | vauthors=Storz P, Hausser A, Link G |title=Protein kinase C [micro] is regulated by the multifunctional chaperon protein p32. |journal=J. Biol. Chem. |volume=275 |issue= 32 |pages= 24601–7 |year= 2000 |pmid= 10831594 |doi= 10.1074/jbc.M002964200 |display-authors=etal|doi-access=free }} *{{cite journal | vauthors=Tye AJ, Ghebrehiwet B, Guo N |title=The human gC1qR/p32 gene, C1qBP. Genomic organization and promoter analysis. |journal=J. Biol. Chem. |volume=276 |issue= 20 |pages= 17069–75 |year= 2001 |pmid= 11278463 |doi= 10.1074/jbc.M009064200 |display-authors=etal|doi-access=free }} *{{cite journal | vauthors=Schaerer MT, Kannenberg K, Hunziker P |title=Interaction between GABA(A) receptor beta subunits and the multifunctional protein gC1q-R. |journal=J. Biol. Chem. |volume=276 |issue= 28 |pages= 26597–604 |year= 2001 |pmid= 11350968 |doi= 10.1074/jbc.M102534200 |display-authors=etal|doi-access=free }} *{{cite journal | vauthors=Kobayashi M, Hanai R |title=M phase-specific association of human topoisomerase IIIbeta with chromosomes. |journal=Biochem. Biophys. Res. Commun. |volume=287 |issue= 1 |pages= 282–7 |year= 2001 |pmid= 11549288 |doi= 10.1006/bbrc.2001.5580 }} *{{cite journal | vauthors=Rozanov DV, Ghebrehiwet B, Postnova TI |title=The hemopexin-like C-terminal domain of membrane type 1 matrix metalloproteinase regulates proteolysis of a multifunctional protein, gC1qR. |journal=J. Biol. Chem. |volume=277 |issue= 11 |pages= 9318–25 |year= 2002 |pmid= 11773076 |doi= 10.1074/jbc.M110711200 |display-authors=etal|doi-access=free }} *{{cite journal | vauthors=Majumdar M, Meenakshi J, Goswami SK, Datta K |title=Hyaluronan binding protein 1 (HABP1)/C1QBP/p32 is an endogenous substrate for MAP kinase and is translocated to the nucleus upon mitogenic stimulation. |journal=Biochem. Biophys. Res. Commun. |volume=291 |issue= 4 |pages= 829–37 |year= 2002 |pmid= 11866440 |doi= 10.1006/bbrc.2002.6491 }} {{refend}}
==External links== * {{UCSC gene info|C1QBP}} {{PDB Gallery|geneid=708}}