CD28 is a single-pass type I transmembrane glycoprotein that belongs to the CD28/CTLA4 (cytotoxic T lymphocyte-associated antigen 4, also known as CD152) family of the immunoglobulin (Ig) superfamily. CD28 and CTLA-4 are structurally homologous molecules and both contain one Ig-like V-type domain in the extracellular region. CD28 and CTLA4 are expressed on the cell surface as disulfide­linked homodimers or as monomers. Together with their ligands, CD80 and CD86, they constitute one of the dominant co-stimulatory pathways that regulate T and B cell responses. CD28 is expressed in T-cells and plasma cells, but not in less mature B-cells. CD28 is involved in T-cell activation, the induction of cell proliferation and cytokine production and promotion of T-cell survival.  CD28 is expressed constitutively on nearly all mouse T cells and surface expression is down­regulated upon ligation of CD28. CTLA­4 is not constitutively expressed but is up­regulated rapidly following T cell activation and CD28 ligation. The binding of CD80 and CD86 to its receptor CD28 induces T-cell proliferation and cytokine production. CD28 ligation has also been shown to regulate Th1/Th2 differentiation. CTLA4 binds to CD80 and CD86 with a 20-100 fold higher affinity than CD28 and is involved in the downregulation of the immune response. The CD80/CD86/CD28/CTLA4 pathway can positively and negatively regulate immune responses. CD28 is thus regarded as a promising therapeutic target for autoimmune diseases and cancer.

CD28 is a single-pass type I transmembrane glycoprotein that belongs to the CD28/CTLA4 (cytotoxic T lymphocyte-associated antigen 4, also known as CD152) family of the immunoglobulin (Ig) superfamily. CD28 and CTLA-4 are structurally homologous molecules and both contain one Ig-like V-type domain in the extracellular region. CD28 and CTLA4 are expressed on the cell surface as disulfide­linked homodimers or as monomers. Together with their ligands, CD80 and CD86, they constitute one of the dominant co-stimulatory pathways that regulate T and B cell responses. CD28 is expressed in T-cells and plasma cells, but not in less mature B-cells. CD28 is involved in T-cell activation, the induction of cell proliferation and cytokine production and promotion of T-cell survival.  CD28 is expressed constitutively on nearly all mouse T cells and surface expression is down­regulated upon ligation of CD28. CTLA­4 is not constitutively expressed but is up­regulated rapidly following T cell activation and CD28 ligation. The binding of CD80 and CD86 to its receptor CD28 induces T-cell proliferation and cytokine production. CD28 ligation has also been shown to regulate Th1/Th2 differentiation. CTLA4 binds to CD80 and CD86 with a 20-100 fold higher affinity than CD28 and is involved in the downregulation of the immune response. The CD80/CD86/CD28/CTLA4 pathway can positively and negatively regulate immune responses. CD28 is thus regarded as a promising therapeutic target for autoimmune diseases and cancer.

 

Product Details

 

Gene Symbol: CD28; TP44; TP-44

 

NCBI Gene ID: 940

 

Uniprot Entry: P10747

 

Construct Details: The recombinant human CD28-Fc fusion is expressed as a 362-amino acid protein consisting of Asn19 - Pro152 region of CD28 (UniProt accession #P10747) and a C-terminal Fc fusion from human IgG1, which exists as a dimer under non-reducing condition.

 

Source:  Human cells stably expressing CD28-Fc and growing in chemical-defined media with no animal components or antibiotics

 

Deduced Amino Acid Sequence:

NKILVKQSPMLVAYDNAVNLSCKYSYNLFSREFRASLHKGLDSAVEVCVVYGNYSQQLQVYSKTGFNCDGKLGNESVTFY

LQNLYVNQTDIYFCKIEVMYPPPYLDNEKSNGTIIHVKGKHLCPSPLFPGPSKPSTGTHTCPPCPAPELLGGPSVFLFPP

KPKDTLMISRTPEVTCVVVDVSHEDPEVKFNWYVDGVEVHNAKTKPREEQYNSTYRVVSVLTVLHQDWLNGKEYKCKVSN

KALPAPIEKTISKAKGQPREPQVYTLPPSREEMTKNQVSLTCLVKGFYPSDIAVEWESNGQPENNYKTTPPVLDSDGSFF

LYSKLTVDKSRWQQGNVFSCSVMHEALHNHYTQKSLSLSPGK

M.W.: Calculated molecular mass 40.7 kDa; estimated by SDS-PAGE under reducing condition 55-60 kDa probably due to glycosylation

 

Calculated PI: 8.19

 

Calculated Extinction Coefficients (M-1 cm-1, at 280nm):  52425

 

Purity: >95% judged by SDS-PAGE under reducing condition (see the gel image above)

 

Formulation: Supplied at 0.5 mg/ml in sterile PBS pH7.4 (carrier and preservative free)

 

Endotoxin Level: <0.1 EU per 1 μg of purified recombinant protein determined by the LAL method

 

Biological Activity: Binds to human B7 family ligands, CD80/B7-1 (SKU#: FCL0716 and FCL0723) and CD86/B7-2 (SKU#: FCL0718 & FCL0725) as well as anti-CD28 monoclonal antibody, human IgG1 (SKU#MAB1827) with high affinity (K_D < 1 nM) determined by ELISA (see Technical Data). Inhibit IL-2 secretion in stimulated human Jurkat T cell cells.  

 

 

 

 

FOR RESEARCH USE ONLY. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE IN HUMAN.

Restriction: This product is not transferable or re-sellable.  Customer obtain no right to transfer, assign, or sublicense its use rights, or to transfer, resell, package, or otherwise distribute the product, or to use the product for the benefit of any third party or for any commercial purpose.  Customer may only use the product in compliance with applicable local, state and federal laws, regulations and rules.  Customer may not directly or indirectly use the product or allow the transfer, transmission, export or re-export of all or any part of the product in violation of any export control law or regulation of the united states or any other relevant jurisdiction.  Your use of this product constitutes acceptance of the terms of this limited use agreement.  Please refer to our “terms & conditions” for details.  If you are not willing to accept the limitation of this agreement, G&P Biosciences will accept return of the product for a full/partial refund.

 

 

Technical Data

  

Recombinant CD28-Fc protein (SKU#FCL0729) was immobilized at 100 ng/well on a 96-well NuncMaxisorp plate for ELISA with serially diluted biotinylated anti-human CD28 monoclonal antibody, human IgG1 (SKU#MAB1827). Biotinyalted anti-CD137 (SKU#MAB1829) human IgG1 was used as a negative control to demonstrate the specificity of CD28 binding under the experimental conditions.  The binding curve was fit and apparent K_D was calculated for anti-CD28: CD28 binding to be 32 ± 3 pM.   

 

 

 

FOR RESEARCH USE ONLY. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE IN HUMAN.

 

Storage

 

The product is shipped at 4°C. Upon receipt, centrifuge the product briefly before opening the vial. It is recommended to store small aliquots at the temperature below –20°C for long-term storage and the product is stable for at least 3 months. The undiluted protein can be stored at 4°C for no more than 2 weeks.

 

 

Use a manual defrost freezer and avoid repeated freeze-thaw cycles.

 

 

 

FOR RESEARCH USE ONLY. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE IN HUMAN.

 

References

 

1. Annu Rev Immunol. 11 :191-212 (1993).

2. Advances in Immunol. 62:131 (1996). 

3. Biochem. J. 318:361 (1996). 

4. Blood 99:2138-2145(2002) 

5. Nat. Immunol. 6:271-279(2005)

 

 

 

Documentation

 

Product datasheet (pdf) can be downloaded here: FCL0729-PDS.pdf

 

 

 

Additional supporting documents, including COA and MSDS are available upon request.

 

 

 

FOR RESEARCH USE ONLY. NOT FOR DIAGNOSTIC OR THERAPEUTIC USE IN HUMAN.

Restriction: This product is not transferable or re-sellable.  Customer obtain no right to transfer, assign, or sublicense its use rights, or to transfer, resell, package, or otherwise distribute the product, or to use the product for the benefit of any third party or for any commercial purpose.  Customer may only use the product in compliance with applicable local, state and federal laws, regulations and rules.  Customer may not directly or indirectly use the product or allow the transfer, transmission, export or re-export of all or any part of the product in violation of any export control law or regulation of the united states or any other relevant jurisdiction.  Your use of this product constitutes acceptance of the terms of this limited use agreement.  Please refer to our “terms & conditions” for details.  If you are not willing to accept the limitation of this agreement, G&P Biosciences will accept return of the product for a full/partial refund.