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- Regulatory Status
- RUO
- Other Names
- T-cell-specific surface glycoprotein CD28, T-Cell Antigen CD28, Tp44, CD28 Molecule, T-Cell-Specific Surface Glycoprotein, CD28 Antigen
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- Product Citations
- publications
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When recombinant human CD28-Fc Chimera is immobilized at 2 µg/mL, biotinylated human CD80 binds in a dose-dependent manner. The EC50 range for this effect is 0.2 - 0.8 µg/mL. HRP Avidin (Cat. No. 405103) was used to detect the binding. -
Stability Testing for Human CD28-Fc Chimera. Recombinant human CD28-Fc Chimera was aliquoted in PBS at 0.2 mg/mL. One aliquot was frozen and thawed four times (4x Freeze/Thaw), and compared to a control kept at 4°C (Control). The samples were tested in a binding assay with biotinylated human CD80.
CD28 was initially identified by antibodies as a 44 kD protein on the membrane of human T cells. CD28 is a 23 kD glycosylated type 1 transmembrane protein, which forms a disulfide-linked homodimer. CD28 is a costimulatory receptor that synergizes with TCR-mediated signals to enhance cytokine production and the proliferation of T cells. CD28 plays a primordial role for the priming of naive T cells. CD28, cytotoxic T-lymphocyte-associated antigen 4 (CTLA-4, CD152), inducible costimulatory (ICOS), programmed death receptor 1 (PD-1), and B- and T- lymphocyte attenuator (BTLA) are members of the family of costimulatory receptors. CD28 and CTLA-4 both bind the same ligands B7-1 (CD80) and B7-2 (CD86). CD28 and ICOS mainly induce T-cell activation whereas CTLA-4, PD-1, and BTLA are inhibitory. In murine plasmacytoid dendritic cells, CD28 signaling induces the downregulation of type I interferon production, which contrasts with its activation role in T cells. CD28 is also expressed on normal murine and human plasma cells (PCs). It promotes PC survival, sustained antibody responses, and the upregulation of transcriptional repressor B lymphocyte-induced maturation protein-1 (Blimp-1), which is a master regulator of PC differentiation. CD28 is also expressed in malignant BM-resident PCs of multiple myeloma (MM) and its overexpression in myeloma cells is associated with bad prognostics. The soluble costimulatory molecule CD28 has been detected in the serum of patients with systemic lupus erythematosus, primary Sjögren's syndrome, and systemic sclerosis. Soluble CD28 results from the shedding of the membrane-bound form.
Product DetailsProduct Details
- Source
- Human CD28, amino acid Asn19-Pro152 (Accession # P10747), with a C-terminal hIgG1 Fc tag, was expressed in CHO cells.
- Molecular Mass
- The 373 amino acid recombinant protein has a predicted molecular mass of approximately 42 kD. The DTT-reduced protein migrates at approximately 60 kD and the non-reduced protein migrates at approximately 120 kD by SDS-PAGE. The predicted N-terminal amino acid is Asn.
- Purity
- >95%, as determined by Coomassie stained SDS-PAGE.
- Formulation
- 0.22 µm filtered protein solution is in PBS, pH7.2
- 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 CD28-Fc Chimera is immobilized at 2 µg/mL, biotinylated human CD80 binds in a dose-dependent manner. The EC50 range for this effect is 0.2 - 0.8 µg/mL. HRP Avidin (Cat. No. 405103) was used to detect the binding.
- Application
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Bioassay
- Application Notes
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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 tech@biolegend.com.
Antigen Details
- Structure
- Homodimer
- Distribution
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CD4, CD8 lymphocytes, immature CD3-, CD8+, CD4+ CD8+ cells, on CD4- CD8- cells, and normal plasma cells
- Function
- Activation of naïve T cells, induction of cytokine production, cell survival, and expression of anti-apoptotic proteins including Bcl-XL.
- Interaction
- Antigen presenting cells
- Ligand/Receptor
- B7-1 (CD80) and B7-2 (CD86)
- Bioactivity
- Measured by its ability to bind biotinylated recombinant human CD80
- Antigen References
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- Hansen JA, et al. 1980. Immunogenetics 5:429-39.
- Gross JA, et al. 1992. J. Immunol. 149:380.
- Coyle AJ and Gutierrez-Ramos JC. 2001. Nat. Immunol. 2:203.
- Hebbar M, et al. 2004. Clin. Exp. Immunol. 136:388.
- Boomer JS and Green JM. 2010. Cold Spring Harb. Perspect Biol. 8:a002436.
- Rozanski CH, et al. 2011. J. Exp. Med. 208:1435.
- Rozanski CH, et al. 2015. J. Immunol. 194:4717.
- Gene ID
- 940 View all products for this Gene ID
- UniProt
- View information about CD28 on UniProt.org
Related FAQs
- Why choose BioLegend recombinant proteins?
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• 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. - How does the activity of your recombinant proteins compare to competitors?
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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!
- What is the specific activity or ED50 of my recombinant protein?
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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.
- Have your recombinants been tested for stability?
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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.
- Does specific activity of a recombinant protein vary between lots?
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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.
- How do you convert activity as an ED50 in ng/ml to a specific activity in Units/mg?
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Use formula Specific activity (Units/mg) = 10^6/ ED50 (ng/mL)
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