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Gene
CFI
Uniprot
P05156
Protein
Complement factor I
See alternative names C3B/C4B inactivator
Uniprot Function Description
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 (PubMed:7360115, PubMed:17320177). Essential cofactors for these reactions include factor H and C4BP in the fluid phase and membrane cofactor protein/CD46 and CR1 on cell surfaces (PubMed:2141838, PubMed:9605165, PubMed:12055245). 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 (PubMed:28671664).
Sample type
Recommended sample types are human plasma and serum. For other sample types e.g cerebrospinal fluid, (CSF), tissue or cell lysate, please contact support@olink.com for more information. Please note that protein expression levels are expected to vary in different sample types and certain assays may be affected by interfering substances such as hemolysate.
Precision
Precision (repeatability) is calculated from linearized NPX values over LOD.
Analytical measuring range
The technical data reported below refers to the measured value in the in vitro validation assays run using known concentrations of recombinant antigen.
Dilution factor
For optimal assay readout, Olink assays are run using different dilutions of the original samples e.g. undiluted, 1:10, or higher. The dilution factor for this assay is noted below and should be taken into account when estimating the appropriate addressable biological concentration of the protein based on the in vitro validation data.
Biomarker Validation Data
Additional validation data, as well as a more detailed description of how the Olink panels are quality controlled can be found in our Data Validation documents – go to Document download center