Gene Symbol: C1QB
Description: complement C1q B chain
Alias: complement C1q subcomponent subunit B, complement C1q chain B, complement component 1, q subcomponent, B chain, complement component 1, q subcomponent, beta polypeptide, complement component C1q, B chain, complement subcomponent C1q chain B
Species: human
Products:     C1QB

Top Publications

  1. Grewal R, Morgan T, Finch C. C1qB and clusterin mRNA increase in association with neurodegeneration in sporadic amyotrophic lateral sclerosis. Neurosci Lett. 1999;271:65-7 pubmed
    ..tissues of sporadic amyotrophic lateral sclerosis (SALS) for mRNA levels of two inflammatory proteins, complement C1qB and clusterin (apoJ)...
  2. van Schaarenburg R, Daha N, Schonkeren J, Nivine Levarht E, van Gijlswijk Janssen D, Kurreeman F, et al. Identification of a novel non-coding mutation in C1qB in a Dutch child with C1q deficiency associated with recurrent infections. Immunobiology. 2015;220:422-7 pubmed publisher
    ..We identified the mutation using deep-sequencing. By qPCR we studied the mRNA expression of C1qA, C1qB and C1qC in the PBMCs of the patient...
  3. Batu E, Kosukcu C, Taşkıran E, Sahin S, Akman S, Sozeri B, et al. Whole Exome Sequencing in Early-onset Systemic Lupus Erythematosus. J Rheumatol. 2018;: pubmed publisher
    ..did not perform WES in 1 patient who had features similar to the first 3 cases; only the exons of C1QA, C1QB, and C1QC were screened with Sanger sequencing...
  4. Yuan H, Chen R, Liu Y, Tariq M, Sun Y, Xia C. Crystallization and preliminary crystallographic studies of the complement 1qA globular domain from zebrafish, Dare-C1qAgD. Acta Crystallogr F Struct Biol Commun. 2014;70:911-4 pubmed publisher
    ..In human, C1q is composed of 18 polypeptide chains: six C1qA chains, six C1qB chains and six C1qC chains...
  5. Kelly K, Liu Y, Zhang J, Dominguez J. Renal C3 complement component: feed forward to diabetic kidney disease. Am J Nephrol. 2015;41:48-56 pubmed publisher
    ..The classic complement pathway was activated in diabetic kidneys with significant increases of C1qa, C1qb, and C1qc mRNAs in DI over LS...
  6. Ma L, Kulesskaya N, Võikar V, Tian L. Differential expression of brain immune genes and schizophrenia-related behavior in C57BL/6N and DBA/2J female mice. Psychiatry Res. 2015;226:211-6 pubmed publisher
    ..mRNA levels of Il1b and Il6 genes were significantly higher in the cortex and hypothalamus, while the mRNA level of C1qb was lower in the cortex, hippocampus and hypothalamus of DBA/2J mice compared to C57BL/6N mice...
  7. Bartling B, Niemann K, Pliquett R, Treede H, Simm A. Altered gene expression pattern indicates the differential regulation of the immune response system as an important factor in cardiac aging. Exp Gerontol. 2019;117:13-20 pubmed publisher
    ..as chemokines (CCLs 6, 8, 9), proteins of the S100 family (S100s 4, 8, 9, 10, 11), complement components (C1qa, C1qb, C1qc, C3, C4b), bacteria/virus-induced genes (lysozyme 1/2, interferon-activated genes), and pro-inflammatory ..
  8. Haure Mirande J, Wang M, Audrain M, Fanutza T, Kim S, Heja S, et al. Integrative approach to sporadic Alzheimer's disease: deficiency of TYROBP in cerebral Aβ amyloidosis mouse normalizes clinical phenotype and complement subnetwork molecular pathology without reducing Aβ burden. Mol Psychiatry. 2019;24:431-446 pubmed publisher
    ..in the switch from homeostatic microglia to disease-associated microglia (DAM), including Trem2, complement (C1qa, C1qb, C1qc, and Itgax), Clec7a and Cst7...
  9. Liu C, Chen J, Yang S, Mao L, Jiang T, Tu H, et al. The Chinese herbal formula Zhibai Dihuang Granule treat Yin-deficiency-heat syndrome rats by regulating the immune responses. J Ethnopharmacol. 2018;225:271-278 pubmed publisher
    ..Plg), Kininogen 1 (Kng1), and significantly decreased levels of Mannose binding lectin 2 (Mbl2) and Complement C1qb chain (C1qb) in ZDG treated rats compared with YDH syndrome rats...

More Information


  1. Navarro Barriuso J, Mansilla M, Naranjo Gómez M, Sanchez Pla A, Quirant Sánchez B, Teniente Serra A, et al. Comparative transcriptomic profile of tolerogenic dendritic cells differentiated with vitamin D3, dexamethasone and rapamycin. Sci Rep. 2018;8:14985 pubmed publisher
    ..However, individually, CYP24A1, MUCL1 and MAP7 for vitD3-tolDC; CD163, CCL18, C1QB and C1QC for dexa-tolDC; and CNGA1 and CYP7B1 for rapa-tolDC, constituted good candidate biomarkers for each ..
  2. Yadav S, Gupta S, Selvaraj C, Doharey P, Verma A, Singh S, et al. In silico and in vitro studies on the protein-protein interactions between Brugia malayi immunomodulatory protein calreticulin and human C1q. PLoS ONE. 2014;9:e106413 pubmed publisher
    ..The molecular docking of BmCRT-C1q complex indicated that C1qB chain (IgG/M and CRP binding sites on C1q) played a major role in the interaction with conserved and non-conserved ..
  3. Ma L, Piirainen S, Kulesskaya N, Rauvala H, Tian L. Association of brain immune genes with social behavior of inbred mouse strains. J Neuroinflammation. 2015;12:75 pubmed publisher
    ..The mRNA levels of H2-d1 in the prefrontal cortex, hippocampus, and hypothalamus and C1qb in the hippocampus of the DBA/2 J strain were significantly down-regulated as compared to those in the C57BL/6 J ..
  4. Tian L, Cao J, Deng X, Zhang C, Qian T, Song X, et al. Unveiling transcription factor regulation and differential co-expression genes in Duchenne muscular dystrophy. Diagn Pathol. 2014;9:210 pubmed publisher
    ..Among the DEGs which shared TFs with DMD, six genes were co-expressed with DMD, including ATP1A2, C1QB, MYOF, SAT1, TRIP10, and IFI6...
  5. Chen M, Ding M, Li Y, Zhong X, Liu S, Guo Z, et al. The complement component 1 q (C1q) in Nile tilapia (Oreochromis niloticus): Functional characterization in host defense against bacterial infection and effect on cytokine response in macrophages. Dev Comp Immunol. 2018;87:98-108 pubmed publisher
    ..In this study, the full-length of C1q subcomponent A, B and C chain genes (C1qA, C1qB and C1qC) were identified and characterized from Nile tilapia (Oreochromis niloticus)...
  6. Lee J, Levin S, Willis E, Li R, Woodruff T, Noakes P. Complement components are upregulated and correlate with disease progression in the TDP-43Q331K mouse model of amyotrophic lateral sclerosis. J Neuroinflammation. 2018;15:171 pubmed publisher
    ..There was a strong negative linear relationship between spinal cord C1qB, C3 and C5aR1 mRNA levels with hind-limb grip strength...
  7. Li J, Ge X, Wang X, Liu X, Ma J. Complement System in the Pathogenesis of Benign Lymphoepithelial Lesions of the Lacrimal Gland. PLoS ONE. 2016;11:e0148290 pubmed publisher
    ..The expression of 14 complement system-related genes in the pathologic tissue, including C2, C3, ITGB2, CR2, C1QB, CR1, ITGAX, CFP, C1QA, C4B|C4A, FANCA, C1QC, C3AR1 and CFHR4, were significantly upregulated while 7 other ..
  8. Goshima M, Sekiguchi R, Matsushita M, Nonaka M. The complement system of elasmobranches revealed by liver transcriptome analysis of a hammerhead shark, Sphyrna zygaena. Dev Comp Immunol. 2016;61:13-24 pubmed publisher
    ..Identified genes were; one C1qB, one C1r, one C1s, one MASP-1/-3, one MASP-2, two factor B/C2, one C3, three C4, one C5, one C6, one C7, one C8A, ..
  9. Wang J, Ma S, Tao R, Xia L, Liu L, Jiang Y. Gene expression profile changes in rat dorsal horn after sciatic nerve injury. Neurol Res. 2017;39:176-182 pubmed publisher
    ..g. ILF3 and LYVE1); and 41 were common in both two groups (e.g. FCER1G, C1QA, C1QB and C1QC)...
  10. Bos S, Phillips M, Watts G, Verhoeven A, Sijbrands E, Ward N. Novel protein biomarkers associated with coronary artery disease in statin-treated patients with familial hypercholesterolemia. J Clin Lipidol. 2017;11:682-693 pubmed publisher
    ..alpha-2-glycoprotein (LRG1), inter-alpha-trypsin inhibitor heavy chain H3, complement C4-B (C4B), complement C1q subcomponent subunit B (C1QB), monocyte differentiation antigen (CD14), and histidine-rich glycoprotein (HRG)...
  11. Lenna S, Assassi S, Farina G, Mantero J, Scorza R, Lafyatis R, et al. The HLA-B*35 allele modulates ER stress, inflammation and proliferation in PBMCs from Limited Cutaneous Systemic Sclerosis patients. Arthritis Res Ther. 2015;17:363 pubmed publisher
    ..Among genes downregulated by HLA-B*35 lentivirus were genes related to complement (C1QB, C1QC), cell cycle (CDNK1A) and apoptosis (Bax, Gadd45)...
  12. Lin P, Nicholls L, Assareh H, Fang Z, Amos T, Edwards R, et al. Transcriptome analysis of human brain tissue identifies reduced expression of complement complex C1Q Genes in Rett syndrome. BMC Genomics. 2016;17:427 pubmed publisher
    ..identified over two hundred differentially expressed genes, and identified the complement C1Q complex genes (C1QA, C1QB and C1QC) as a point of convergence between gene expression changes in human and mouse Rett syndrome brain...
  13. Jin Y, Zhao C, Chen L, Liu X, Pan S, Ju D, et al. Identification of novel gene and pathway targets for human epilepsy treatment. Biol Res. 2016;49:3 pubmed publisher
    ..In down-co-expression module, C1QB (complement C1s), C1S (complement component 1, S subcomponent) and CFI (complement factor I) were enriched in GO:..
  14. Park Y, Kang J, Lee D, Kim M, Bak Y, Yang Y, et al. Interleukin-32α modulates promyelocytic leukemia zinc finger gene activity by inhibiting protein kinase Cɛ-dependent sumoylation. Int J Biochem Cell Biol. 2014;55:136-43 pubmed publisher
    ..Together, our data suggest that IL-32α associates with PLZF and PKCɛ, and then inhibits PLZF sumoylation, resulting in suppression of the transcriptional activity of PLZF. ..
  15. Luo Y, Robinson S, Fujita J, Siconolfi L, MAGIDSON J, Edwards C, et al. Transcriptome profiling of whole blood cells identifies PLEK2 and C1QB in human melanoma. PLoS ONE. 2011;6:e20971 pubmed publisher
    ..Of these, a 2-gene signature consisting of PLEK2 and C1QB led to the best result that correctly classified 93.3% melanoma patients and 90% healthy controls...
  16. Boyd Y, Cockburn D, Holt S, Munro E, van Ommen G, Gillard B, et al. Mapping of 12 translocation breakpoints in the Xp21 region with respect to the locus for Duchenne muscular dystrophy. Cytogenet Cell Genet. 1988;48:28-34 pubmed
    ..All the DMD-associated translocation breakpoints examined lie at several sites within the DMD locus and between the two non-DMD breakpoints. ..
  17. Vanhecke D, Roumenina L, Wan H, Osthoff M, Schaller M, Trendelenburg M. Identification of a major linear C1q epitope allows detection of systemic lupus erythematosus anti-C1q antibodies by a specific peptide-based enzyme-linked immunosorbent assay. Arthritis Rheum. 2012;64:3706-14 pubmed publisher
    ..The ELISA using this peptide was more specific and more sensitive than a conventional anti-C1q assay for the detection of active nephritis in SLE patients. ..
  18. Agarwal V, Sroka M, Fulde M, Bergmann S, Riesbeck K, Blom A. Binding of Streptococcus pneumoniae endopeptidase O (PepO) to complement component C1q modulates the complement attack and promotes host cell adherence. J Biol Chem. 2014;289:15833-44 pubmed publisher
  19. Marquart H, Schejbel L, Sjoholm A, Martensson U, Nielsen S, Koch A, et al. C1q deficiency in an Inuit family: identification of a new class of C1q disease-causing mutations. Clin Immunol. 2007;124:33-40 pubmed
    ..None of 100 healthy controls carried the mutation. Our findings define a third class of molecular mechanisms behind C1q deficiency, where missense mutations cause a lack of detectable C1q-antigen in serum. ..
  20. Bozzini S, Falcone V, Conaldi P, Visai L, Biancone L, Dolei A, et al. Heparin-binding domain of human fibronectin binds HIV-1 gp120/160 and reduces virus infectivity. J Med Virol. 1998;54:44-53 pubmed
    ..Thus, Fn that is present in plasma and mucinous secretions may well affect HIV infectivity and virus distribution in vivo. ..
  21. Reid K. Isolation, by partial pepsin digestion, of the three collagen-like regions present in subcomponent Clq of the first component of human complement. Biochem J. 1976;155:5-17 pubmed
    ..50% higher than expected from the amino acid sequence data. This is probably due to the high collagen-like sequence content of these fragments. ..
  22. Szabo J, Cervenak L, Toth F, Prohaszka Z, Horvath L, Kerekes K, et al. Soluble gC1q-R/p33, a cell protein that binds to the globular "heads" of C1q, effectively inhibits the growth of HIV-1 strains in cell cultures. Clin Immunol. 2001;99:222-31 pubmed
    ..Since gC1q-R is a human protein, it is most probably not antigenic in humans. It would seem logical, therefore, to consider gC1q-R or its fragments involved in the CD4 binding as potential therapeutic agents. ..
  23. Roumenina L, Ruseva M, Zlatarova A, Ghai R, Kolev M, Olova N, et al. Interaction of C1q with IgG1, C-reactive protein and pentraxin 3: mutational studies using recombinant globular head modules of human C1q A, B, and C chains. Biochemistry. 2006;45:4093-104 pubmed
    ..Thus, a recently proposed model suggesting the rotation of the gC1q domain upon ligand recognition may be extended to C1q interaction with CRP and PTX3 in addition to IgG1. ..
  24. Kraft A, McPherson C, Harry G. Association Between Microglia, Inflammatory Factors, and Complement with Loss of Hippocampal Mossy Fiber Synapses Induced by Trimethyltin. Neurotox Res. 2016;30:53-66 pubmed publisher
    ..At 2 days, C1q protein was evident in the CA3 with elevated C1qa, C1qb, C3, Cr3a, and Cr3b mRNA levels...
  25. Klegeris A, Bissonnette C, Dorovini Zis K, McGeer P. Expression of complement messenger RNAs by human endothelial cells. Brain Res. 2000;871:1-6 pubmed
    ..In addition to C6 mRNA, C1q and C9 were not detected in ECV304 cells. These results indicate that endothelial cells may be a source of complement proteins in brain and other organs of the body. ..
  26. Hidvegi T, Prohaszka Z, Ujhelyi E, Thielens N, Dierich M, Hampl H, et al. Studies on the mechanism of complement-mediated inhibition of antibody binding to HIV gp41. Clin Exp Immunol. 1993;94:490-3 pubmed
  27. Quinkal I, Hernandez J, Chevallier S, Arlaud G, Vernet T. Mapping of the interaction between the immunodominant loop of the ectodomain of HIV-1 gp41 and human complement protein C1q. Eur J Biochem. 1999;265:656-63 pubmed
    ..It is proposed that the recognition of gp41 by C1q is driven by hydrophobic interactions, and that the sites of gp41 responsible for interaction with gp120 and C1q partly overlap. ..
  28. Zakharyan R, Khoyetsyan A, Arakelyan A, Boyajyan A, Gevorgyan A, Stahelova A, et al. Association of C1QB gene polymorphism with schizophrenia in Armenian population. BMC Med Genet. 2011;12:126 pubmed publisher
    ..schizophrenia in Armenian population, focusing on four frequent single nucleotide polymorphisms (SNPs) of C1QA and C1QB genes...
  29. Reid K. Complete amino acid sequences of the three collagen-like regions present in subcomponent C1q of the first component of human complement. Biochem J. 1979;179:367-71 pubmed
    ..The B- and C-chains have alanine residues at positions B-9 and C-36 where glycine might be expected. The A-chain has a threonine residue at position A-39, which is located between two Gly-X-Y triplets. ..
  30. Prohaszka Z, Nemet K, Csermely P, Hudecz F, Mezo G, Fust G. Defensins purified from human granulocytes bind C1q and activate the classical complement pathway like the transmembrane glycoprotein gp41 of HIV-1. Mol Immunol. 1997;34:809-16 pubmed
  31. Stoiber H, Thielens N, Ebenbichler C, Arlaud G, Dierich M. The envelope glycoprotein of HIV-1 gp120 and human complement protein C1q bind to the same peptides derived from three different regions of gp41, the transmembrane glycoprotein of HIV-1, and share antigenic homology. Eur J Immunol. 1994;24:294-300 pubmed
    ..These data suggest that in addition to functional homology between C1q and gp120 structural homology between these two molecules exists. This molecular mimicry might become the basis for immunologically relevant autoimmune phenomena. ..
  32. Prohaszka Z, Hidvegi T, Ujhelyi E, Stoiber H, Dierich M, Susal C, et al. Interaction of complement and specific antibodies with the external glycoprotein 120 of HIV-1. Immunology. 1995;85:184-9 pubmed
    ..Addition of specific antibodies did not increase complement activation by rgp120 and only in the case of a monoclonal antibody to the V3-loop could we see complement-dependent inhibition of antibody binding. ..
  33. Kouser L, Madhukaran S, Shastri A, Saraon A, Ferluga J, Al Mozaini M, et al. Emerging and Novel Functions of Complement Protein C1q. Front Immunol. 2015;6:317 pubmed publisher
    ..C1q role in synaptic pruning, and thus CNS development, its anti-cancer effects as an immune surveillance molecule, and possibly in aging are currently areas of extensive research. ..
  34. Gorgani N, Parish C, Easterbrook Smith S, Altin J. Histidine-rich glycoprotein binds to human IgG and C1q and inhibits the formation of insoluble immune complexes. Biochemistry. 1997;36:6653-62 pubmed
    ..The results show that human HRG binds to C1q and to IgG in a Zn2+-modulated fashion, and that HRG can regulate the formation of IIC in vitro, thus indicating a new functional role for HRG in vivo. ..
  35. Ebenbichler C, Thielens N, Vornhagen R, Marschang P, Arlaud G, Dierich M. Human immunodeficiency virus type 1 activates the classical pathway of complement by direct C1 binding through specific sites in the transmembrane glycoprotein gp41. J Exp Med. 1991;174:1417-24 pubmed
    ..These data provide the first experimental evidence of a direct interaction between the C1 complex and HIV-1, and indicate that C1 binding and activation are mediated by specific sites in gp41. ..
  36. Duus K, Thielens N, Lacroix M, Tacnet P, Frachet P, Holmskov U, et al. CD91 interacts with mannan-binding lectin (MBL) through the MBL-associated serine protease-binding site. FEBS J. 2010;277:4956-64 pubmed publisher
    ..These findings demonstrate that MBL and L-ficolin interact with CD91, strongly suggesting that they have the potential to function as soluble recognition molecules for scavenging microbial and apoptotic material by CD91. ..
  37. McAdam R, Goundis D, Reid K. A homozygous point mutation results in a stop codon in the C1q B-chain of a C1q-deficient individual. Immunogenetics. 1988;27:259-64 pubmed
    ..No material corresponding to the A or C chains, or a truncated B chain, could be identified by antigenic analysis of the patient's serum, indicating that a complete B chain is required for secretion of a C1q molecule. ..
  38. Chew C, Chua K, Lian L, Puah S, Tan S. PCR-RFLP genotyping of C1q mutations and single nucleotide polymorphisms in Malaysian patients with systemic lupus erythematosus. Hum Biol. 2008;80:83-93 pubmed
    Five types of known mutations within the C1q gene [located at C1qA-Gln186 (C >T), C1qB-Gly15 (G >A), C1qB-Arg150 (C >T), C1qC-Gly6 (G >A), and C1qC-Arg41 (C >T)] and two SNPs located at C1qA-Gly70 (G/A) and C1qC-Pro14 (T/C) ..
  39. Thielens N, Bally I, Ebenbichler C, Dierich M, Arlaud G. Further characterization of the interaction between the C1q subcomponent of human C1 and the transmembrane envelope glycoprotein gp41 of HIV-1. J Immunol. 1993;151:6583-92 pubmed
  40. Reid K. Molecular cloning and characterization of the complementary DNA and gene coding for the B-chain of subcomponent C1q of the human complement system. Biochem J. 1985;231:729-35 pubmed
    ..Nucleotide sequencing of the 5' end of the gene indicates the presence of a predominantly hydrophobic stretch of 29 amino acids, immediately before residue B1, which could serve as a signal peptide. ..
  41. Sellar G, Cockburn D, Reid K. Localization of the gene cluster encoding the A, B, and C chains of human C1q to 1p34.1-1p36.3. Immunogenetics. 1992;35:214-6 pubmed
  42. Carbutt S, Duff J, Yarnall A, Burn D, Hudson G. Variation in complement protein C1q is not a major contributor to cognitive impairment in Parkinson's disease. Neurosci Lett. 2015;594:66-9 pubmed publisher
    ..the links between C1q and cognitive function we assessed the genetic variability of the C1q encoding genes: C1QA, C1QB and C1QC between PD patients and matched controls...
  43. Trouw L, Daha N, Kurreeman F, Böhringer S, Goulielmos G, Westra H, et al. Genetic variants in the region of the C1q genes are associated with rheumatoid arthritis. Clin Exp Immunol. 2013;173:76-83 pubmed publisher
    ..We genotyped single nucleotide polymorphisms (SNPs) in and around the C1q genes, C1qA, C1qB and C1qC, in a Dutch set of 845 RA cases and 1046 controls...
  44. Hamad O, Nilsson P, Wouters D, Lambris J, Ekdahl K, Nilsson B. Complement component C3 binds to activated normal platelets without preceding proteolytic activation and promotes binding to complement receptor 1. J Immunol. 2010;184:2686-92 pubmed publisher
    ..However, the generation of C3(H(2)O) represents nonproteolytic activation of C3 and after factor I cleavage may act as a ligand for receptor binding. ..
  45. Pednekar L, Pathan A, Paudyal B, Tsolaki A, Kaur A, Abozaid S, et al. Analysis of the Interaction between Globular Head Modules of Human C1q and Its Candidate Receptor gC1qR. Front Immunol. 2016;7:567 pubmed publisher
  46. Su H, Boackle R. Interaction of the envelope glycoprotein of human immunodeficiency virus with C1q and fibronectin under conditions present in human saliva. Mol Immunol. 1991;28:811-7 pubmed
    ..e. to the salivary sediment), may play an important role in the reduction of HIV transmission via saliva. Further studies will be needed to test the latter speculation. ..
  47. Peters K, Davis W, Ito J, Winfield K, Stoll T, Bringans S, et al. Identification of Novel Circulating Biomarkers Predicting Rapid Decline in Renal Function in Type 2 Diabetes: The Fremantle Diabetes Study Phase II. Diabetes Care. 2017;40:1548-1555 pubmed publisher
    ..the ability of plasma apolipoprotein (apo) A-IV (apoA4), apo C-III, CD5 antigen-like (CD5L), complement C1q subcomponent subunit B (C1QB), complement factor H-related protein 2, and insulin-like growth factor binding protein 3 (..
  48. Petry F. Molecular basis of hereditary C1q deficiency. Immunobiology. 1998;199:286-94 pubmed
  49. Chen G, Tan C, Teh B, Lu J. Molecular mechanisms for synchronized transcription of three complement C1q subunit genes in dendritic cells and macrophages. J Biol Chem. 2011;286:34941-50 pubmed publisher
    ..The three human C1q genes are closely bundled on chromosome 1 (C1qA-C1qC-C1qB) and their basal and IFN?-stimulated expression, largely restricted to macrophages and dendritic cells, is ..
  50. Nauta A, Bottazzi B, Mantovani A, Salvatori G, Kishore U, Schwaeble W, et al. Biochemical and functional characterization of the interaction between pentraxin 3 and C1q. Eur J Immunol. 2003;33:465-73 pubmed
    ..These results indicate that PTX3 can both inhibit and activate the classical complement pathway by binding C1q, depending on the way it is presented. PTX3 may therefore be involved in the regulation of the innate immune response. ..
  51. Stoiber H, Ebenbichler C, Thielens N, Arlaud G, Dierich M. HIV-1 rsgp41 depends on calcium for binding of human c1q but not for binding of gp120. Mol Immunol. 1995;32:371-4 pubmed
    ..Thus, calcium is required for the interaction between rsgp41 and C1q, whereas the interaction between rsgp41 and gp120 is independent of divalent cations. ..
  52. van Schaarenburg R, Suurmond J, Habets K, Brouwer M, Wouters D, Kurreeman F, et al. The production and secretion of complement component C1q by human mast cells. Mol Immunol. 2016;78:164-170 pubmed publisher
    ..Fully differentiated mast cells were shown by both RNA sequencing and qPCR to express C1QA, C1QB and C1QC. C1q produced by mast cells has a similar molecular make-up as serum C1q...
  53. Kishore U, Gupta S, Perdikoulis M, Kojouharova M, Urban B, Reid K. Modular organization of the carboxyl-terminal, globular head region of human C1q A, B, and C chains. J Immunol. 2003;171:812-20 pubmed
    ..The heterotrimeric organization thus offers functional flexibility and versatility to the whole C1q molecule. ..
  54. Son M, Diamond B, Santiago Schwarz F. Fundamental role of C1q in autoimmunity and inflammation. Immunol Res. 2015;63:101-6 pubmed publisher
  55. Sellar G, Blake D, Reid K. Characterization and organization of the genes encoding the A-, B- and C-chains of human complement subcomponent C1q. The complete derived amino acid sequence of human C1q. Biochem J. 1991;274 ( Pt 2):481-90 pubmed
  56. Kojouharova M, Panchev I, Tchorbadjieva M, Reid K, Hoppe H. Differential binding of IgG and of a HIV gp41 peptide by the B chain and A chain globular head sequences of C1q, respectively. J Immunol. 1998;161:4325-31 pubmed
  57. Thielens N, Tacnet Delorme P, Arlaud G. Interaction of C1q and mannan-binding lectin with viruses. Immunobiology. 2002;205:563-74 pubmed
    ..These interactions lead to virus inactivation, are independent of complement activation and are influenced by the oligomerization state of the collectin. ..
  58. Dardiotis E, Koutsou P, Zamba Papanicolaou E, Vonta I, Hadjivassiliou M, Hadjigeorgiou G, et al. Complement C1Q polymorphisms modulate onset in familial amyloidotic polyneuropathy TTR Val30Met. J Neurol Sci. 2009;284:158-62 pubmed publisher
    ..05). Our study has identified polymorphisms which may influence the FAP-TTR Val30Met phenotype. Identifying modifier genes and their protein products may contribute to therapeutic advances. ..
  59. Kojouharova M, Gadjeva M, Tsacheva I, Zlatarova A, Roumenina L, Tchorbadjieva M, et al. Mutational analyses of the recombinant globular regions of human C1q A, B, and C chains suggest an essential role for arginine and histidine residues in the C1q-IgG interaction. J Immunol. 2004;172:4351-8 pubmed
  60. Hinkelbein J, Jansen S, Iovino I, Kruse S, Meyer M, Cirillo F, et al. Thirty Minutes of Hypobaric Hypoxia Provokes Alterations of Immune Response, Haemostasis, and Metabolism Proteins in Human Serum. Int J Mol Sci. 2017;18: pubmed publisher
    ..1 ± 1.3% to 89.2 ± 1.8% during HH. Expression of 14 spots (i.e., 10 proteins: ALB, PGK1, APOE, GAPDH, C1QA, C1QB, CAT, CA1, F2, and CLU) was significantly altered...
  61. Reid K, Thompson E. Amino acid sequence of the N-terminal 108 amino acid residues of the B chain of subcomponent C1q of the first component of human complement. Biochem J. 1978;173:863-8 pubmed
    ..The exact position of the interchain disulphide bond joining the A and B chains of human subcomponent C1q was shown to be between residues A4 and B4. ..
  62. Reid K, Bentley D, Wood K. Cloning and characterization of the complementary DNA for the B chain of normal human serum C1q. Philos Trans R Soc Lond B Biol Sci. 1984;306:345-54 pubmed
  63. Bally I, Ancelet S, Moriscot C, Gonnet F, Mantovani A, Daniel R, et al. Expression of recombinant human complement C1q allows identification of the C1r/C1s-binding sites. Proc Natl Acad Sci U S A. 2013;110:8650-5 pubmed publisher
    ..The expression method reported here opens the way for deciphering the molecular basis of the unusual binding versatility of C1q by mapping the residues involved in the sensing of its targets and the binding of its receptors. ..
  64. Tissot B, Gonnet F, Iborra A, Berthou C, Thielens N, Arlaud G, et al. Mass spectrometry analysis of the oligomeric C1q protein reveals the B chain as the target of trypsin cleavage and interaction with fucoidan. Biochemistry. 2005;44:2602-9 pubmed
    ..Given the involvement of the C1q globular heads in the recognition of IgG, this interaction may account for the observed anticomplementary activity of fucoidan. ..
  65. Rafiq S, Frayling T, Vyse T, Cunninghame Graham D, Eggleton P. Assessing association of common variation in the C1Q gene cluster with systemic lupus erythematosus. Clin Exp Immunol. 2010;161:284-9 pubmed publisher
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    ..As a result, C1r2C1s2 was displaced from C1q, and the C1 complex was deactivated. This novel function of the Cna-like MSCRAMMs represents a potential immune evasion strategy that could be used by numerous Gram-positive pathogens. ..