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Gene Review

C1QBP  -  complement component 1, q subcomponent...

Homo sapiens

Synonyms: ASF/SF2-associated protein p32, C1qBP, Complement component 1 Q subcomponent-binding protein, mitochondrial, GC1QBP, Glycoprotein gC1qBP, ...
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Disease relevance of C1QBP


Psychiatry related information on C1QBP

  • This article reports the structural chromosomal anomaly in three patients with mental retardation: (i) Proband was a five year old girl with reciprocal retardation (1; 2) (p32; q11) (ii) Proband, female of 14 years [6].

High impact information on C1QBP

  • Factor XII binds primarily to cell surface u-PAR (urokinase plasminogen activator receptor); HK binds to gC1qR via its light chain (domain 5) and to cytokeratin 1 by its heavy chain (domain 3) and, to a lesser degree, by its light chain [7].
  • Endothelial cells (HUVECs) have bimolecular complexes of u-PAR-cytokeratin 1 and gC1qR-cytokeratin 1 at the cell surface plus free gC1qR, which is present in substantial molar excess [7].
  • Internalin interacts specifically with human E-cadherin, whereas InlB activates the tyrosine kinase receptor Met and also interacts with the ubiquitous receptor gC1qR and proteoglycans [8].
  • Interaction between complement receptor gC1qR and hepatitis C virus core protein inhibits T-lymphocyte proliferation [9].
  • The deletion mutant was also found in lysosomal compartments in HeLa cells expressing only the p33 form of the invariant chain [10].

Biological context of C1QBP


Anatomical context of C1QBP

  • Upon PMA stimulation of normal rat fibroblast (F111) and transformed (HeLa) cells, the HABP1 level in the cytoplasm gradually decreased with a parallel increase in the nucleus [12].
  • In HeLa cells, within 6 h of PMA treatment, HABP1 was completely translocated to the nucleus, which was prevented by PD98059, a selective inhibitor of ERK [12].
  • Treatment of endothelial cells with anti gC1qR monoclonal antibody F(ab')(2) fragments reduced C4d deposition by approximately 20% (n=5, p<0.05) [14].
  • Cellular localization by immunofluorescence staining revealed that p32 is present in the cell throughout the cytosol and nucleus, whereas CBF is present primarily in the nucleus [16].
  • We have previously demonstrated that hepatitis C virus (HCV) core, the first protein to be expressed and circulating in the blood of infected individuals, inhibited human T cell proliferative response through interaction with the complement receptor, globular domain of C1q receptor (gC1qR) [17].

Associations of C1QBP with chemical compounds

  • To substantiate our findings prior to the cisplatin treatment, the expression of HABP1 was reduced by small interfering RNA mediated knockdown [15].
  • We found that core protein binds the gC1qR displayed on the cell surface of monocyte/macrophages and inhibits the production of IL-12p70 upon lipopolysaccharide stimulation [18].
  • We have analyzed the interaction of PKC mu with p32 in detail, and we show here in vivo association of PKC mu, as revealed from yeast two-hybrid analysis, precipitation assays using glutathione S-transferase fusion proteins, and reciprocal coimmunoprecipitation [19].
  • In contrast, platelet activation with TRAP, epinephrine, or ADP produced markedly increased gC1qR expression as reflected by 74.5.2 binding but not 60.11 binding [20].
  • Whereas PAC-1 binding to activated platelets could be reversed following platelet incubation with PGE1, 74.5.2 binding remained unchanged, suggesting the sustained expression of gC1qR following platelet stimulation [20].
  • The inhibitory effect of p32 on MLTU transcription appears to require the CAAT box element in the major late promoter, suggesting that p32 may become tethered to the MLTU via an interaction with the CAAT box binding transcription factor [21].

Physical interactions of C1QBP

  • The major MT1-MMP cleavage site (Gly(79) down arrow Gln(80)) is localized within the structurally disordered loop connecting the beta(3) and the beta(4) strands of gC1qR [11].
  • In contrast, HK did not affect TFPI-2 binding to gC1qR [22].
  • Although p32 binds to the kinase domain of PKC mu, it does not serve as a substrate [19].
  • Taken together, these data suggest that HABP1 induces morphological changes and modulates the cell cycle by interacting with proteins like CDC 25 through its N-terminal alpha-helix [23].
  • The studies on the interaction of these proteins, using dot-blot analysis, revealed that cytokeratin 1 binds to both gC1qR and u-PAR while gC1qR and u-PAR do not bind to each other [24].

Regulatory relationships of C1QBP

  • HCV core-mediated expression of IL-8 was inhibited by blocking gC1qR, a known receptor for soluble HCV core linked to MAPK signaling [25].
  • Specifically, chronic core isolates bind to gC1qR more efficiently and inhibit T-cell proliferation as well as gamma interferon (IFN-gamma) production more profoundly than resolved core isolates [26].
  • OBJECTIVE: The hyaluronan-binding protein TSG-6 (tumor necrosis factor-stimulated gene 6) forms a stable complex with the serine protease inhibitor, inter-alpha-inhibitor, potentiates the inhibition of plasmin activity, and has antiinflammatory effects in vivo [27].
  • OBJECTIVE: TSG-6 [the product of tumor necrosis factor (TNF)-stimulated gene-6] is a hyaluronan-binding protein that is present in the synovial fluids of arthritis patients and is secreted by cells of articular joints (e.g. chondrocytes and synoviocytes) [28].
  • Hyaluronan binding protein 1 (HABP1) is a ubiquitously expressed multifunctional phospho-protein that interacts with a wide range of ligands and is implicated in cell signalling [29].

Other interactions of C1QBP

  • Here, we report that gC1qR is susceptible to MT1-MMP proteolysis in vitro and in cell cultures [11].
  • Taken together, these data suggest that gC1qR may participate in tissue remodeling and inflammation by localizing TFPI-2 to the pericellular environment to modulate local protease activity and regulate HK activation [22].
  • The cellular protein p32 was isolated originally as a protein tightly associated with the essential splicing factor ASF/SF2 during its purification from HeLa cells [13].
  • We have earlier reported that overexpression of HABP1 in fibroblast cells causes perturbed cell growth, extensive vacuolation and restricted entry to the S-phase, finally leading to apoptosis (Biochem Biophys Res Commun 2003; 300: 686-693) [15].
  • We report the selective inhibition of TLR4-induced IL-12 production after cross-linking of gC1qR on the surface of macrophages and dendritic cells [4].

Analytical, diagnostic and therapeutic context of C1QBP


  1. Receptor for the globular heads of C1q (gC1q-R, p33, hyaluronan-binding protein) is preferentially expressed by adenocarcinoma cells. Rubinstein, D.B., Stortchevoi, A., Boosalis, M., Ashfaq, R., Ghebrehiwet, B., Peerschke, E.I., Calvo, F., Guillaume, T. Int. J. Cancer (2004) [Pubmed]
  2. Human p32 protein relieves a post-transcriptional block to HIV replication in murine cells. Zheng, Y.H., Yu, H.F., Peterlin, B.M. Nat. Cell Biol. (2003) [Pubmed]
  3. gC1q-R/p32, a C1q-binding protein, is a receptor for the InlB invasion protein of Listeria monocytogenes. Braun, L., Ghebrehiwet, B., Cossart, P. EMBO J. (2000) [Pubmed]
  4. gC1q receptor ligation selectively down-regulates human IL-12 production through activation of the phosphoinositide 3-kinase pathway. Waggoner, S.N., Cruise, M.W., Kassel, R., Hahn, Y.S. J. Immunol. (2005) [Pubmed]
  5. The overexpression of RHAMM, a hyaluronan-binding protein that regulates ras signaling, correlates with overexpression of mitogen-activated protein kinase and is a significant parameter in breast cancer progression. Wang, C., Thor, A.D., Moore, D.H., Zhao, Y., Kerschmann, R., Stern, R., Watson, P.H., Turley, E.A. Clin. Cancer Res. (1998) [Pubmed]
  6. Structural chromosomal anomaly in mental retardation. Reddy, K.S., Rajangam, S., Thomas, I.M. Indian journal of pediatrics. (1999) [Pubmed]
  7. Formation of bradykinin: a major contributor to the innate inflammatory response. Joseph, K., Kaplan, A.P. Adv. Immunol. (2005) [Pubmed]
  8. Invasion of mammalian cells by Listeria monocytogenes: functional mimicry to subvert cellular functions. Cossart, P., Pizarro-Cerdá, J., Lecuit, M. Trends Cell Biol. (2003) [Pubmed]
  9. Interaction between complement receptor gC1qR and hepatitis C virus core protein inhibits T-lymphocyte proliferation. Kittlesen, D.J., Chianese-Bullock, K.A., Yao, Z.Q., Braciale, T.J., Hahn, Y.S. J. Clin. Invest. (2000) [Pubmed]
  10. Regulation of intracellular trafficking of human CD1d by association with MHC class II molecules. Kang, S.J., Cresswell, P. EMBO J. (2002) [Pubmed]
  11. The hemopexin-like C-terminal domain of membrane type 1 matrix metalloproteinase regulates proteolysis of a multifunctional protein, gC1qR. Rozanov, D.V., Ghebrehiwet, B., Postnova, T.I., Eichinger, A., Deryugina, E.I., Strongin, A.Y. J. Biol. Chem. (2002) [Pubmed]
  12. Hyaluronan binding protein 1 (HABP1)/C1QBP/p32 is an endogenous substrate for MAP kinase and is translocated to the nucleus upon mitogenic stimulation. Majumdar, M., Meenakshi, J., Goswami, S.K., Datta, K. Biochem. Biophys. Res. Commun. (2002) [Pubmed]
  13. The splicing factor-associated protein, p32, regulates RNA splicing by inhibiting ASF/SF2 RNA binding and phosphorylation. Petersen-Mahrt, S.K., Estmer, C., Ohrmalm, C., Matthews, D.A., Russell, W.C., Akusjärvi, G. EMBO J. (1999) [Pubmed]
  14. Classical pathway complement activation on human endothelial cells. Yin, W., Ghebrehiwet, B., Weksler, B., Peerschke, E.I. Mol. Immunol. (2007) [Pubmed]
  15. Upregulation of hyaluronan binding protein 1 (HABP1/p32/gC1qR) is associated with Cisplatin induced apoptosis. Kamal, A., Datta, K. Apoptosis (2006) [Pubmed]
  16. Human p32, interacts with B subunit of the CCAAT-binding factor, CBF/NF-Y, and inhibits CBF-mediated transcription activation in vitro. Chattopadhyay, C., Hawke, D., Kobayashi, R., Maity, S.N. Nucleic Acids Res. (2004) [Pubmed]
  17. Hepatitis C virus core protein inhibits human T lymphocyte responses by a complement-dependent regulatory pathway. Yao, Z.Q., Nguyen, D.T., Hiotellis, A.I., Hahn, Y.S. J. Immunol. (2001) [Pubmed]
  18. Hepatitis C virus core selectively suppresses interleukin-12 synthesis in human macrophages by interfering with AP-1 activation. Eisen-Vandervelde, A.L., Waggoner, S.N., Yao, Z.Q., Cale, E.M., Hahn, C.S., Hahn, Y.S. J. Biol. Chem. (2004) [Pubmed]
  19. Protein kinase C [micro] is regulated by the multifunctional chaperon protein p32. Storz, P., Hausser, A., Link, G., Dedio, J., Ghebrehiwet, B., Pfizenmaier, K., Johannes, F.J. J. Biol. Chem. (2000) [Pubmed]
  20. Activation-dependent surface expression of gC1qR/p33 on human blood platelets. Peerschke, E.I., Murphy, T.K., Ghebrehiwet, B. Thromb. Haemost. (2003) [Pubmed]
  21. Cellular splicing and transcription regulatory protein p32 represses adenovirus major late transcription and causes hyperphosphorylation of RNA polymerase II. Ohrmalm, C., Akusjärvi, G. J. Virol. (2006) [Pubmed]
  22. Tissue factor pathway inhibitor-2 (TFPI-2) recognizes the complement and kininogen binding protein gC1qR/p33 (gC1qR): implications for vascular inflammation. Peerschke, E.I., Petrovan, R.J., Ghebrehiwet, B., Ruf, W. Thromb. Haemost. (2004) [Pubmed]
  23. HABP1/p32/gC1qR induces aberrant growth and morphology in Schizosaccharomyces pombe through its N-terminal alpha helix. Mallick, J., Datta, K. Exp. Cell Res. (2005) [Pubmed]
  24. Interaction of high molecular weight kininogen binding proteins on endothelial cells. Joseph, K., Tholanikunnel, B.G., Ghebrehiwet, B., Kaplan, A.P. Thromb. Haemost. (2004) [Pubmed]
  25. Induction of p38- and gC1qR-dependent IL-8 expression in pulmonary fibroblasts by soluble hepatitis C core protein. Moorman, J.P., Fitzgerald, S.M., Prayther, D.C., Lee, S.A., Chi, D.S., Krishnaswamy, G. Respir. Res. (2005) [Pubmed]
  26. SOCS1 and SOCS3 are targeted by hepatitis C virus core/gC1qR ligation to inhibit T-cell function. Yao, Z.Q., Waggoner, S.N., Cruise, M.W., Hall, C., Xie, X., Oldach, D.W., Hahn, Y.S. J. Virol. (2005) [Pubmed]
  27. TSG-6 expression in human articular chondrocytes. Possible implications in joint inflammation and cartilage degradation. Maier, R., Wisniewski, H.G., Vilcek, J., Lotz, M. Arthritis Rheum. (1996) [Pubmed]
  28. Up-regulation and differential expression of the hyaluronan-binding protein TSG-6 in cartilage and synovium in rheumatoid arthritis and osteoarthritis. Bayliss, M.T., Howat, S.L., Dudhia, J., Murphy, J.M., Barry, F.P., Edwards, J.C., Day, A.J. Osteoarthr. Cartil. (2001) [Pubmed]
  29. Constitutive expression of hyaluronan binding protein 1 (HABP1/p32/gC1qR) in normal fibroblast cells perturbs its growth characteristics and induces apoptosis. Meenakshi, J., Anupama, n.u.l.l., Goswami, S.K., Datta, K. Biochem. Biophys. Res. Commun. (2003) [Pubmed]
  30. In vitro interaction between human immunodeficiency virus type 1 Rev protein and splicing factor ASF/SF2-associated protein, p32. Tange, T.O., Jensen, T.H., Kjems, J. J. Biol. Chem. (1996) [Pubmed]
  31. Surface expression of complement receptor gC1q-R/p33 is increased on the plasma membrane of human spermatozoa after capacitation. Grace, K.S., Bronson, R.A., Ghebrehiwet, B. Biol. Reprod. (2002) [Pubmed]
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