Recombinant Human Complement factor I (CFI)

Code CSB-EP005279HU
Size $256
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  • (Tris-Glycine gel) Discontinuous SDS-PAGE (reduced) with 5% enrichment gel and 15% separation gel.
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Product Details

Greater than 85% as determined by SDS-PAGE.
Not Test
Target Names
Uniprot No.
Research Area
Alternative Names
C3B/C4B inactivator
Homo sapiens (Human)
Expression Region
Target Protein Sequence
Note: The complete sequence including tag sequence, target protein sequence and linker sequence could be provided upon request.
Mol. Weight
70.5 kDa
Protein Length
Full Length of Mature Protein
Tag Info
N-terminal 6xHis-tagged
Liquid or Lyophilized powder
Note: We will preferentially ship the format that we have in stock, however, if you have any special requirement for the format, please remark your requirement when placing the order, we will prepare according to your demand.
If the delivery form is liquid, the default storage buffer is Tris/PBS-based buffer, 5%-50% glycerol. If the delivery form is lyophilized powder, the buffer before lyophilization is Tris/PBS-based buffer, 6% Trehalose, pH 8.0.
We recommend that this vial be briefly centrifuged prior to opening to bring the contents to the bottom. Please reconstitute protein in deionized sterile water to a concentration of 0.1-1.0 mg/mL.We recommend to add 5-50% of glycerol (final concentration) and aliquot for long-term storage at -20℃/-80℃. Our default final concentration of glycerol is 50%. Customers could use it as reference.
Troubleshooting and FAQs
Storage Condition
Store at -20°C/-80°C upon receipt, aliquoting is necessary for mutiple use. Avoid repeated freeze-thaw cycles.
Shelf Life
The shelf life is related to many factors, storage state, buffer ingredients, storage temperature and the stability of the protein itself.
Generally, the shelf life of liquid form is 6 months at -20°C/-80°C. The shelf life of lyophilized form is 12 months at -20°C/-80°C.
Lead Time
Delivery time may differ from different purchasing way or location, please kindly consult your local distributors for specific delivery time.
Repeated freezing and thawing is not recommended. Store working aliquots at 4℃ for up to one week.
Datasheet & COA
Please contact us to get it.

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Target Background

Trypsin-like serine protease that plays an essential role in regulating the immune response by controlling all complement pathways. Inhibits these pathways by cleaving three peptide bonds in the alpha-chain of C3b and two bonds in the alpha-chain of C4b thereby inactivating these proteins. Essential cofactors for these reactions include factor H and C4BP in the fluid phase and membrane cofactor protein/CD46 and CR1 on cell surfaces. The presence of these cofactors on healthy cells allows degradation of deposited C3b by CFI in order to prevent undesired complement activation, while in apoptotic cells or microbes, the absence of such cofactors leads to C3b-mediated complement activation and subsequent opsonization.
Gene References into Functions
  1. This study has revealed a significant genetic role for CFI-rs13104777 in acute anterior uveitis. This influence may be dependent on human leukocyte antigen (HLA)-B27 and disease laterality. PMID: 27380463
  2. An extremely rare, heterozygous mutation in the gene encoding CFI likely affecting splicing was associated for the first time with atypical hemolytic uremic syndrome. PMID: 28455885
  3. this study illustrates the importance of early versus late diagnosis of CFI deficiency PMID: 28942469
  4. This finding although rare does suggest that screening for chromosomal rearrangements affecting CFI should be undertaken in all aHUS patients particularly if the factor I level is unexplainably low. PMID: 27268256
  5. 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
  6. Taken together, our data argue that multiple rare and ultra-rare alleles in CFI contribute to AMD pathogenesis; they improve the precision of the assessment of the contribution of CFI to AMD PMID: 28282489
  7. Case Report: thrombotic microangiopathy with mutations in complement factor I and thrombomodulin. PMID: 26613809
  8. Our results indicate that CFI polymorphisms are not significantly associated with VKH syndrome. PMID: 26900322
  9. Patients with advanced atrophic AMD carried these rare variants more frequently than patients with neovascular AMD (11 of 93 [11.8%] vs 40 of 835 [4.8%]; P = .04). PMID: 26767664
  10. Low FI levels are strongly associated with rare CFI variants and age-related macular degeneration. PMID: 25788521
  11. A missense variant (p.V412M) in CFI was discovered in two Tunisian Jewish families with early-onset age-related macular degeneration. PMID: 25986072
  12. Regulatory components of the alternative complement pathway in endothelial cell cytoplasm, factor H and factor I, are not packaged in Weibel-Palade bodies. PMID: 25803806
  13. In this study, the odds of AMD were highest in those with deficient vitamin D status and 2 risk alleles for the CFH and CFI genotypes, suggesting a synergistic effect between vitamin D status and complement cascade protein function. PMID: 26312598
  14. iC3b level, a proteolytically inactive form of C3b, was lower in HCV infected patient sera, reflecting impairment of both C3 convertase and Factor I activity. PMID: 24983375
  15. association between rs10033900 and age-related macular degeneration risk in Han Chinese population PMID: 24642830
  16. The mutations in the regulators CFH, CFI and MCP involve loss-of-function, whereas those for C3 involve gain-of-function. PMID: 25188723
  17. The CFI p.Gly119Arg mutation was identified in 7/521 age-related macular degeneration cases compared to 1/627 age-matched controls; this mutation confers a high risk of disease. PMID: 25352734
  18. CFI genetic variants played an important role in the development of NSCLC in Chinese population. PMID: 25394898
  19. High expression of complement factor I is associated with recurrence in breast cancer. PMID: 25618258
  20. results provide evidence for the role of CFI in the progression of cSCC and identify it as a potential therapeutic target in this nonmelanoma skin cancer PMID: 25184960
  21. This study has revealed a significant association between acute anterior uveitis (AAU) and CFI-rs7356506, suggesting that CFI is involved in the pathogenesis of AAU PMID: 25075123
  22. Neither of the two SNPs most studied (rs10033900 or rs2285714) in the CFI gene was a risk factor for developing neovascular age-related macular degeneration or polypoidal choroidal vasculopathy in a Chinese population. PMID: 24732209
  23. Recurrent aseptic meningo-encephalitis is a rare clinical presentation of complete FI deficiency. PMID: 24142231
  24. An STR polymorphism in intron 7 of human CFI gene on chromosome 4q in 11 Asian populations indicated that Group H alleles in exon 11 of the CFI gene were almost entirely confined to East Asian populations, making it useful in forensic anthropology. PMID: 23688582
  25. We found that 7.8% of advanced age-related macular degeneration cases compared to 2.3% of controls are carriers of rare missense CFI variants. PMID: 24036952
  26. Case Report: patient with atypical haemolytic uremic syndrome with combined membrane cofactor protein CD46 and complement factor I mutations undergoing successful kidney transplantation. PMID: 23519521
  27. Mutations in complement factor I protein is associated with end-stage renal disease in a patient with hemolytic uremic syndrome caused by infections by Escherichia coli strains producing Shiga-like toxins. PMID: 23731345
  28. these findings demonstrate that rare, highly penetrant mutations in CFI contribute to the genetic burden of age-related macular degeneration. PMID: 23685748
  29. rs1136287 in CFI is less likely to be associated in in extremely myopic Japanese individuals. PMID: 23722394
  30. The alternative pathway of complement may play a role in the pathogenesis of HELLP syndrome. PMID: 22594569
  31. Acute hemorrhagic leukoencephalitis (AHLE) is an unreported, rare phenotype for partial complement factor I deficiency. PMID: 22926405
  32. we report four novel mutations and the first large gene deletion in the CFI locus. PMID: 22710145
  33. One SNP (rs10033900) in the CFI gene, which encodes a protein involved in the inflammatory pathway, was significantly associated with myopic choroidal neovascularization in multivariate analysis after correction for multiple testing. PMID: 22678500
  34. Since FI requires cofactors for its activity we also investigated the binding of purified cofactors C4BP and FH and found acquisition of both proteins, which retained their activity in FI mediated degradation of C3b and C4b. PMID: 22514678
  35. factor I were significantly diminished early after trauma. PMID: 22258234
  36. all analyzed cofactors form similar trimolecular complexes with FI and C3b/C4b, and the accessibility of FIMAC and SP domains is crucial for the function of FI PMID: 22393059
  37. Results question whether complement factor I autoantibodies per se predispose to atypical hemolytic uremic syndrome. PMID: 22223611
  38. Forster resonance energy transfer was used to investigate the 10 muM K(D) (210 kD) complex between the N-terminal region of the soluble complement regulator, factor H (FH1-4), and the key activation-specific complement fragment, C3b. PMID: 21936007
  39. Data show that FI is in a proteolytically inactive form, demonstrating that it circulates in a zymogen-like state. PMID: 21768352
  40. Study describes the molecular and functional consequences of two novel mutations of FI. PMID: 21316765
  41. Study identified novel mutations in CFH, CFHR5, CFI, CFB and C3 in American patients with atypical hemolytic uremic syndrome. PMID: 20513133
  42. Role of a common variant near the complement factor I gene in susceptibility to age-related macular degeneration. PMID: 20087399
  43. In a large cohort of 202 patients with aHUS, we identified 23 patients carrying exonic mutations in CFI PMID: 20016463
  44. the FIMAC domain appears to harbor the main binding sites important for the ability of FI to degrade C4b and C3b PMID: 20044478
  45. mutations in complement factor I affect both secretion and function of factor I, which leads to impaired regulation of the complement system in atypical hemolytic uremic syndrome. PMID: 19877009
  46. the last 45 amino acid of the heavy chain, including a disulfide bridge area, did not participate in the serine protease function of factor I PMID: 14967308
  47. Human complement factor I does not require cofactors for cleavage of synthetic substrates. PMID: 15210795
  48. fI and the serine protease domain were found to have similar amidolytic activities but strikingly different proteolytic activities on C3(NH(3)). PMID: 15835912
  49. Mutations in the complement regulators factor H, membrane cofactor protein (MCP), and factor I are associated with atypical hemolytic uremic syndrome. PMID: 16386793
  50. factor I in concert with CR1 on E and factor H in serum due to their cofactor activity are likely to be important contributors PMID: 16920989

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Involvement in disease
Hemolytic uremic syndrome atypical 3 (AHUS3); Complement factor I deficiency (CFI deficiency); Macular degeneration, age-related, 13 (ARMD13)
Subcellular Location
Secreted, extracellular space. Secreted.
Protein Families
Peptidase S1 family
Tissue Specificity
Expressed in the liver by hepatocytes. Also present in other cells such as monocytes, fibroblasts or keratinocytes.
Database Links

HGNC: 5394

OMIM: 217030

KEGG: hsa:3426

STRING: 9606.ENSP00000378130

UniGene: Hs.312485

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