|Synonyms||CD28 antigen (Tp44); CD28 antigen; CD28 molecule; CD28|
|Description||Human CD28 is composed of four exons encoding a protein of 220 amino acids that is expressed on the cell surface as a glycosylated, disulfide-linked homodimer of 44 kDa. Members of the CD28 family share a number of common features. These receptors consist of paired V-set immunoglobulin superfamily (IgSF) domains attached to single transmembrane domains and cytoplasmic domains that contain critical signaling motifs. The CD28 and CTLA4 ligands, CD80 and CD86, consist of single V-set and C1-set IgSF domains. The interaction of these costimulatory receptors with ligands is mediated through the MYPPPY motif within the receptor V-set domains. CD28 is expressed constitutively on almost all human CD4 T cells and approximately 50% of CD8 T cells. CD28 costimulation has diverse effects on T cell function, including biochemical events at the immunological synapse, downstream phosphorylation and other post-translational modifications, transcriptional changes, and cytoskeletal remodeling. At the most basic level, CD28 signals increase a cell’s glycolytic rate, allowing cells to generate the energy necessary for growth and proliferation.
Recombinant Human CD28 Fc Chimera produced in HEK293 cells is a polypeptide chain containing 363 amino acids with the C-termimal human IgG1 Fc fragment. A fully biologically active molecule, rhCD28 has a molecular mass of 66-70 kDa analyzed by reducing SDS-PAGE and is obtained by chromatographic techniques at GenScript.
|Biological Activity||Immobilized human CD28 Fcat 2μg/mL (100μL/well) can bind human Biotin-B7-1(CD80) Fc with a linear range of 0.01-0.5μg/mL when detected by Streptavidin-HRP second antibody.|
Asn¹⁹-Pro¹⁵² (Accession #: P10747), expressed with a C-terminal human IgG1 Fc fragment.
|Measured Molecular Weight||66~70 kDa, observed by reducing SDS-PAGE.|
|Purity||> 97% as analyzed by reducing SDS-PAGE.|
|Formulation||Lyophilized from a 0.2 μm filtered solution in PBS.|
|Reconstitution||Reconstituted in ddH₂O or PBS at 100 μg/ml.|
|Endotoxin Level||< 0.2 EU/μg, determined by LAL method.|
|Storage||Lyophilized recombinant CD28 Fc Chimera, Human remains stable up to 6 months at lower than -70°C from date of receipt. Upon reconstitution, Human CD28 Fc Chimera should be stable up to 1 week at 4°C or up to 3 months at -20°C. For long term storage it is recommended that a carrier protein (example 0.1% BSA) be added. Avoid repeated freeze-thaw cycles.|
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