Description / CD28-Fc
CTLA-4 and CD28 are receptors of the immunoglobulin superfamily that are expressed, along with the transmembrane glycoproteins B7-1 and B7-2, by antigen-presenting cells, and with these ligands constitute crucial co-stimulatory pathways for T and B cell regulatory responses. It is through engagement with CD28 and CTLA-4 that the B7 family ligands B7-1 and B7-2 play principal roles in immunity by activating immune response and maintaining immune tolerance. Co-stimulatory signals generated by B7-1 and B7-2 interactions with CD28 serve to stimulate T cell activation and prevent anergy through the amplification of T cell receptor (TCR) signaling. In contrast, interactions of the ligands with CTLA-4 serves to maintain T cell homeostasis and self-tolerance through the disruption of stimulatory signaling from B7 isoform-bound CD28 complexes, and by inducing powerful inhibitory signals in T cells. CTLA-4, like B7-1, is only poorly expressed on resting dendritic cells; therefore, up-regulation of their interaction and resultant amplification and regulation of T cell activity at peripheral inflammation sites is considerably delayed upon immune activation. Conversely, B7-2 and CD28 are constitutively expressed by resting hematopoietic and T cells, respectively, and as a result are able to rapidly induce up-regulation upon immune activation, making them critical to the early co-stimulatory signaling of immune response. Unlike B7-1 and B7-2, the ligands PD-L1 (or B7-H1) and B7-H2, which also belong to the B7 family, have not been shown to influence immunity through interaction with CTLA-4. B7-H2 has been shown to have restricted interaction with CD28. The difference in expression of B7-1, B7-2 and B7-H2 may enable temporally and spatially-specific regulation of T cell response through non-competitive CD28 interaction. Recombinant Human sCD28 Fc is a glycosylated, disulfide-linked homodimer of 734 amino acid residues whose monomer consists of the 134-amino-acid length extracellular portion of CD28 fused to the 231-amino-acid length Fc portion of human IgG1 by two glycines. The calculated molecular weight of Recombinant Human sCD28 Fc dimer is 82.4 kDa; however, due to glycosylation, the monomer and dimer migrate at apparent molecular weights of approximately 60-70 kDa and 150–160 kDa by SDS-PAGE analysis under reducing conditions.
More Information
Size | 20 µg |
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Source | CHO cells |
Biological Activity | Determined by its ability to bind its principal binding partner (B7-1) in a functional ELISA. |
Purity Confirmation | >95% by SDS-PAGE & HPLC analysis |
Length [aa] | 367 |
Molecular Weight | 82.4 kDa |
Species Reactivity | Human |
Formulation | lyophilized |
Protein Sequence | NKILVKQSPM LVAYDNAVNL SCKYSYNLFS REFRASLHKG LDSAVEVCVV YGNYSQQLQV YSKTGFNCDG KLGNESVTFY LQNLYVNQTD IYFCKIEVMY PPPYLDNEKS NGTIIHVKGK HLCPSPLFPG PSKPGGPKSC DKTHTCPPCP APELLGGPSV FLFPPKPKDT LMISRTPEVT CVVVDVSHED PEVKFNWYVD GVEVHNAKTK PREEQYNSTY RVVSVLTVLH QD |
Synonyms | soluble CD28 Fc, T-cell-specific surface glycoprotein CD28, TP44 |
Uniprot ID | P10747 |
Protein RefSeq | NP_006130.1 |
mRNA RefSeq | NM_006139.3 |