C3是一種補(bǔ)體系統(tǒng)的蛋白質(zhì)，在炎癥和感染等免疫應(yīng)答過程中發(fā)揮重要作用。C3能夠通過與其他補(bǔ)體蛋白質(zhì)相互作用，激活免疫細(xì)胞、引導(dǎo)炎癥反應(yīng)和溶解病原菌等。近年來的研究表明，C3不僅僅在免疫應(yīng)答中發(fā)揮作用，還參與調(diào)節(jié)胰島素信號(hào)通路和代謝調(diào)節(jié)等生物學(xué)過程。C3的含量和功能異常與多種疾病的發(fā)生發(fā)展密切相關(guān)，如糖尿病、心血管疾病和肝病等。

C3 plays a central role in the activation of the complement system. Its processing by C3 convertase is the central reaction in both classical and alternative complement pathways. After activation C3b can bind covalently, via its reactive thioester, to cell surface carbohydrates or immune aggregates.; Derived from proteolytic degradation of complement C3, C3a anaphylatoxin is a mediator of local inflammatory process. In chronic inflammation, acts as a chemoattractant for neutrophils. It induces the contraction of smooth muscle, increases vascular permeability and causes histamine release from mast cells and basophilic leukocytes.; Acts as a chemoattractant for neutrophils in chronic inflammation.; adipogenic hormone that stimulates triglyceride (TG) synthesis and glucose transport in adipocytes, regulating fat storage and playing a role in postprandial TG clearance. Appears to stimulate TG synthesis via activation of the PLC, MAPK and AKT signaling pathways. Ligand for C5AR2. Promotes the phosphorylation, ARRB2-mediated internalization and recycling of C5AR2.

1. Evasion of C3b deposition at division septa and lateral amplification underneath the capsule requires localization of the FH-binding protein PspC at division sites. PMID: 30139996
2. Clinical Manifestation of Patients With Atypical Hemolytic Uremic Syndrome With the C3 p.I1157T Variation in the Kinki Region of Japan. PMID: 29695177
3. In our meta-analysis, C3 genetic polymorphisms unveiled a positive effect on the risk of advanced age-related macular degeneration, especially in Caucasians PMID: 30352574
4. Case Report: recurrent proliferative glomerulonephritis with persistent isolated C3 deposition. PMID: 29968411
5. A phage Ab against C3b that inhibited the alternative complement pathway, but not the classical pathway, was described in 2009. Studies using this Ab in a variety of assays have now demonstrated that it acts primarily by inhibiting tickover, thereby confirming that tickover really exists. PMID: 28855277
6. Anti-HLA class I and class II C3d-binding donor-specific antibodies carried a twofold and 1.5-fold increased risk of kidney graft loss, respectively. PMID: 29265514
7. Study shows no significant association of the C3 gene with uveitis, suggesting C3 confers either no or limited risk for uveitis susceptibility. PMID: 28408754
8. Here we have shown for the first time, that ligand- or insulin-mediated activation of PPARgamma in human hepatoma cell line HepG2 causes the downregulation of C3 gene expression and protein secretion PMID: 29550264
9. Single Nucleotide Polymorphism rs11569514 in C3 and haplotypes of C3 variants were associated with schizophrenia in a Han Chinese population. PMID: 29742493
10. alphaXbeta2 uses the alphaX alphaI domain to bind iC3b on its C3c moiety at one of two sites. PMID: 28292891
11. findings revealed a significant association between variant p.R102G in complement component C3 gene with exudative age-related macular degeneration in the Tunisian population PMID: 28470643
12. SNPs within the complement genes may contribute to IA, the first step to type 1 diabetes, with at least one SNP in C3 significantly associated with clinically diagnosed type 1 diabetes. PMID: 27306948
13. An increase in serum C4, as well as a decrease in C3, was an important outcome determinant for patients with immunoglobulin A nephropathy. PMID: 28697742
14. rituximab was not effective in few cases of complement-mediated C3 glomerulonephritis and dense deposit disease . Despite promising results in immunoglobulin-associated and idiopathic Membranoproliferative glomerulonephritis, current evidence on this treatment remains weak, and controlled and prospective data are urgently needed. PMID: 28573137
15. C3F polymorphism is associated with viral infections and protection from rejection after liver transplantation. PMID: 27801525
16. Pra1 targets C3 by cleaving C3 at a unique site. This inhibited effector function of the activation fragments. The newly formed C3a-like peptide lacked the C-terminal arginine residue needed for C3a-receptor binding and activation. Pra1 also bound to C3a and C3b generated by human convertases and blocked their effector functions, C3a binding to human C3a receptor, C3 antifungal activity, and C3b deposition. PMID: 28860090
17. data provide the first evidence that T17M rhodopsin mutant disrupts C3 secretion via the induction of ROS and the suppression of TWIST1. PMID: 28569420
18. High C3 was significantly associated with incidence of diabetes after risk factor adjustments PMID: 29029276
19. This study enclosed strong synergistic association of risk genotypes of C3 and CFH Y402H with AMD. We also revealed synergistic influence of CCL2-2518 and the at-risk genotype of the C3 in AMD with an estimated AP = 50.9% (adjusted AP = 24.7%). Present findings show that CCL2-2518 polymorphism is not an innocent bystander in AMD susceptibility when combined with the at-risk genotype of C3 (R102G). PMID: 28095095
20. Our study shows C3 to be a relatively strong susceptibility gene for advanced-type-AMD (exudative-and-geographic-atrophy) in an Iranian population. PMID: 27029644
21. BBB disruption is present in ACS, and elevated levels of IL-6 and C3 in CSF in diffuse NPSLE PMID: 29036223
22. mobilizes dental pulp stem cells and specifically guides pulp fibroblast recruitment PMID: 27497510
23. This study uncovers the origin of the effect of ionic strength on C3d-CR2 interaction and deepens the understanding of the molecular mechanism of their interaction, which is valuable for the design of vaccines and small molecule inhibitors. PMID: 27154286
24. Studies indicate that the complement response lie the active fragments, C3a and C5a, acting through their specific receptors, C3aR, C5aR1 and C5aR2 to direct the cellular response to inflammation. PMID: 28576324
25. Plasma C3b levels are significantly increased in thrombotic microangiopathy patients after allogeneic stem cell transplantation. PMID: 28801815
26. Findings indicate that recognition of C3-opsonized Francisella tularensis, but not extensive cytosolic replication, plays an important role in regulating macrophage viability during intracellular infections with type A F. tularensis. PMID: 28739830
27. exposure of neural stem cells to neutrophil-synthesized concentrations of C1q and C3a promoted astrogliogenesis and cell migrationtion. PMID: 28687659
28. THP appears to participate directly in complement inactivation by its ability to act as a cofactor for C3b degradation. PMID: 28742158
29. These data suggest that locally produced C3 is an important prosurvival mechanism in pancreatic beta-cells under a proinflammatory assault. PMID: 28582497
30. many types of human cells specifically internalized C3(H2O), the hydrolytic product of C3, and not native C3, from the extracellular milieu. PMID: 28192370
31. Decreased C5a expression is associated with increased inflammation in cystic fibrosis. PMID: 28278205
32. Results show that expression of C3 was significantly increased in tumors from patients having a poor response to chemoradiation therapy. PMID: 27254108
33. C3d-positive glomerular staining is an independent risk factor for the development of end-stage renal disease in ANCA-associated renal vasculitis. PMID: 27257040
34. Factor I binds C3b-Factor H between Factor H domains 2 and 3 and a reoriented C3b C-terminal domain and docks onto the first scissile bond, while stabilizing its catalytic domain for proteolytic activity. PMID: 28671664
35. The VEGF haplotype TGA could be used as a marker for poor visual prognosis in Tunisian patients with neovascular AMD treated with bevacizumab. PMID: 27116510
36. C3 SNP rs2277984 may be a potential biomarker for predicting metabolic syndrome risk in patients receiving clozapine treatment. PMID: 26503818
37. Strikingly C3, the central component of complement, plays a crucial role in the adherence of Brugia malayi to vascular endothelial cells. PMID: 28481947
38. The uromodulin-CFH interaction enhanced the cofactor activity of CFH for factor I-mediated cleavage of C3b to inactivated C3b. PMID: 27113631
39. Generated monoclonal antibody that can only bind to C3d when it manifests itself as the final end product of cleaved C3. PMID: 28174050
40. C3 was strongly associated with insulin sensitivity after bariatric surgery. PMID: 28188738
41. Study reveals structural differences and similarities between C3(H2O), its progenitor C3, and its functional analogue C3b. Data suggest that C3(H2O) generation is accompanied by the migration of the thioester-containing domain of C3 from one end of the molecule to the other. PMID: 27250206
42. human neutrophil peptides 1-3 and complement activation fragments iC3b were higher in patients with acute thrombotic thrombocytopenic purpura - indicating a role of innate immunity in acute autoimmune TTP. PMID: 27662014
43. The data suggest a common evolutionary origin for both inhibitory mechanisms, called decay acceleration and cofactor activity, with variable C3b binding through domains at sites ii, iii, and iv, and provide a framework for understanding regulators of complement activation (RCA) disease-related mutations and immune evasion. PMID: 27013439
44. CFH, ARMS2, and C3 were associated with specific features of neovascularization at the time patients were enrolled in Comparison of Age-Related Macular Degeneration Treatments Trials . PMID: 27099955
45. Elevated C3a is able to predict the mortality following cardiac resynchronization therapy of heart failure PMID: 27492980
46. Decreased serum C3 may have a role in renal pathology classification for patients with silent but not with overt lupus nephritis PMID: 27900491
47. Decreased transcription of C3R mRNA was found in patients with Type 2 Diabetes as compared to non-diabetics. PMID: 27291248
48. analyzed C5 c.2654G>A and C3 gene polymorphism in 220 Chinese patients PMID: 27307199
49. this paper shows that chymase may control C3-related pathology in cutaneous vasculitis PMID: 27465068
50. Case Report: severe active C3 glomerulonephritis triggered by immune complexes treated with eculizumab. PMID: 27717365

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Complement component 3 deficiency (C3D); Macular degeneration, age-related, 9 (ARMD9); Hemolytic uremic syndrome atypical 5 (AHUS5)

Secreted.

Plasma. The acylation stimulating protein (ASP) is expressed in adipocytes and released into the plasma during both the fasting and postprandial periods.

HGNC: 1318

OMIM: 120700

KEGG: hsa:718

STRING: 9606.ENSP00000245907

UniGene: Hs.529053