Biolegend, 789004, Recombinant Human CD19-Fc Chimera (carrier-free), 25μg

CD19 is a 95 kD transmembrane glycoprotein that functions as a co-receptor for the B-cell antigen receptor (BCR) complex on B lymphocytes. CD19 is expressed throughout B cell development, and it is commonly used as a B-cell lineage marker. CD19 plays an important role in B-cell activation and humoral immune responses. It is required for the responsiveness of mature B cells to antigen stimulation, germinal center development, and antibody affinity maturation. CD19's association with the BCR, CD81, CD38, CD21, CD22, and IFITM1/CD225/Leu13 enables CD19 to amplify B-cell signaling and decreases the threshold for activation of downstream signaling pathways and for triggering B-cell responses to antigens. CD19 activates signaling pathways that lead to the activation of phosphatidylinositol 3-kinase and the mobilization of intracellular Ca 2+ stores. CD19 polymorphisms are associated with the development of autoimmunity by promoting autoantibody production. Homozygous mutations in CD19 cause a type of hypogammaglobulinemia in which the response of mature B cells to antigenic stimulation is defective.
25μg
Source: Human CD19, amino acid Glu21-Lys291 (Accession # P15391) with a C-terminal IgG1 Fc and 6-His tag was expressed in CHO.
Molecular Mass: The 515 amino acid recombinant protein has a predicted molecular mass of approximately 57.5 kD. The DTT-reduced protein migrates at approximately 75 kD and the non-reduced protein migrate at approximately 150 kD by SDS-PAGE. The predicted N-terminal amino acid is Glu.
Purity: >95%, as determined by Coomassie stained SDS-PAGE.
Formulation: 0.22 µm filtered protein solution is in PBS
Endotoxin Level: Less than 0.1 EU per µg protein as determined by the LAL method.
Concentration: 10 and 25 µg sizes are bottled at 200 µg/mL. 100 µg size and larger sizes are lot-specific and bottled at the concentration indicated on the vial. To obtain lot-specific concentration and expiration, please enter the lot number in our Certificate of Analysis online tool.
Storage & Handling: Unopened vial can be stored between 2°C and 8°C for up to 2 weeks, at -20°C for up to six months, or at -70°C or colder until the expiration date. For maximum results, quick spin vial prior to opening. The protein can be aliquoted and stored at -20°C or colder. Stock solutions can also be prepared at 50 - 100 µg/mL in appropriate sterile buffer, carrier protein such as 0.2 - 1% BSA or HSA can be added when preparing the stock solution. Aliquots can be stored between 2°C and 8°C for up to one week and stored at -20°C or colder for up to 3 months. Avoid repeated freeze/thaw cycles.
Activity: When recombinant human CD19-Fc Chimera is immobilized at 2 µg/mL, biotinylated human CD81-Fc Chimera binds in a dose-dependent manner. The EC50 range for this effect is 100 - 400 ng/mL. HRP Avidin (Cat. No. 405103) was used to detect the binding.
Application: Bioassay
Application Notes: BioLegend carrier-free recombinant proteins provided in liquid format are shipped on blue ice. Our comparison testing data indicates that when handled and stored as recommended, the liquid format has equal or better stability and shelf-life compared to commercially available lyophilized proteins after reconstitution. Our liquid proteins are verified in-house to maintain activity after shipping on blue ice and are backed by our 100% satisfaction guarantee. If you have any concerns, contact us at [email protected].
Product Citations: Cheng K, et al. 2023. Int J Mol Sci. 24:. PubMed Prinz LF, et al. 2024. Cell Rep Med. 101421:5. PubMed Pan J, et al. 2021. J Cell Mol Med. 25:1089. PubMed
Structure: Covalently linked homodimer
Distribution: Detected on marginal zone and germinal center B cells in lymph nodes, detected on blood B cells
Function: Functions as a co-receptor for the B-cell antigen receptor (BCR) complex on B lymphocytes
Interaction: B cell
Ligand/Receptor: CD21, CD81
Bioactivity: Measured by its ability to bind human CD81
Cell Type: B cells
Biology Area: Adaptive Immunity, Immuno-Oncology, Immunology
Molecular Family: Soluble Receptors
Antigen References: de Rie MA, et al. 1989. Cell Immunol. 118:368-81. Carter RH, et al. 1992. Science. 256:105-107. Buhl AM, et al. 1997. J Exp Med. 186:1897-910. Sato S, et al. 1997. J Immunol. 159:3278-87. Wang Y, et al. 2002. Immunity. 17:501-14. van Zelm MC, et al. 2006. N Engl J Med. 354:1901-12.
Gene ID: 930
UniProt: View information about CD19 on UniProt.org
Regulatory Status: RUO
Other Names: B-lymphocyte antigen CD19, CD19 Molecule, CD19 Antigen, B-Lymphocyte Surface Antigen B4, T-Cell Surface Antigen Leu-12, Differentiation Antigen CD19, CVID3
Q: Why choose BioLegend recombinant proteins?
A: • Each lot of product is quality-tested for bioactivity as indicated on the data sheet.
     • Greater than 95% Purity or higher, tested on every lot of product.
     • 100% Satisfaction Guarantee for quality performance, stability, and consistency.
     • Ready-to-use liquid format saves time and reduces challenges associated with reconstitution.
     • Bulk and customization available. Contact us.
     • Learn more about our Recombinant Proteins.
Q: How does the activity of your recombinant proteins compare to competitors?
A: We quality control each and every lot of recombinant protein. Not only do we check its bioactivity, but we also compare it against other commercially available recombinant proteins. We make sure each recombinant protein’s activity is at least as good as or better than the competition’s. In order to provide you with the best possible product, we ensure that our testing process is rigorous and thorough. If you’re curious and eager to make the switch to BioLegend recombinants, contact your sales representative today!
Q: What is the specific activity or ED50 of my recombinant protein?
A: The specific activity range of the protein is indicated on the product datasheets. Because the exact activity values on a per unit basis can largely fluctuate depending on a number of factors, including the nature of the assay, cell density, age of cells/passage number, culture media used, and end user technique, the specific activity is best defined as a range and we guarantee the specific activity of all our lots will be within the range indicated on the datasheet. Please note this only applies to recombinants labeled for use in bioassays. ELISA standard recombinant proteins are not recommended for bioassay usage as they are not tested for these applications.
Q: Have your recombinants been tested for stability?
A: Our testing shows that the recombinant proteins are able to withstand room temperature for a week without losing activity. In addition the recombinant proteins were also found to withstand four cycles of freeze and thaw without losing activity.
Q: Does specific activity of a recombinant protein vary between lots?
A: Specific activity will vary for each lot and for the type of experiment that is done to validate it, but all passed lots will have activity within the established ED50 range for the product and we guarantee that our products will have lot-to-lot consistency. Please conduct an experiment-specific validation to find the optimal ED50 for your system.
Q: How do you convert activity as an ED50 in ng/ml to a specific activity in Units/mg?
A: Use formula Specific activity (Units/mg) = 10^6/ ED50 (ng/mL)