CD28 and CTLA-4, together with their ligands, B7-1 and B7-2, constitute one of the dominant co-stimulatory pathways that regulate T and B cell responses. CD28 and CTLA-4 are structurally homologous molecules that are members of the immunoglobulin (Ig) gene superfamily. Both CD28 and CTLA-4 are composed of a single Ig V-like extracellular domain, a transmembrane domain and an intracellular domain. CD28 and CTLA-4 are both expressed on the cell surface as disulfide-linked homodimers or as monomers. The genes encoding these two molecules are closely linked on human chromosome 2 and mouse chromosome 1. Mouse CD28 is expressed constitutively on virtually 100% of mouse T cells and on developing thymocytes. Cell surface expression of mouse CD28 is down-regulated upon ligation of CD28 in the presence of PMA or PHA. In contrast, CTLA-4 is not expressed constitutively but is up-regulated rapidly following T cell activation and CD28 ligation. Cell surface expression of mouse CTLA-4 peaks approximately 48 hours after activation. Although both CTLA-4 and CD28 can bind to the same ligands, CTLA-4 binds to B7-1 and B7-2 with a 20-100 fold higher affinity than CD28. CD28/B7 interaction has been shown to prevent apoptosis of activated T cells via the up-regulation of bcl-XL. CD28 ligation has also been shown to regulate Th1/Th2 differentiation.
Post-translational: Phosphorylated by LCK (PubMed:7568038). Dephosphorylated by PTPN11 (PubMed:36114179). Tyrosine phosphorylated induced by CD40LG.
生物活性
Immobilized Recombinant Human CD28 Protein (rp231841) at 1.0 μg/mL can bind Theralizumab (anti-CD28) (Ab190136) with the EC50 of 249.3 ng/mL.
We recommend that this vial be briefly centrifuged prior to opening to bring the contents to the bottom. Reconstitute at 1.0 mg/mL in sterile distilled water. Stock solutions should be apportioned into working aliquots and stored at ≤ -20 °C. Further dilutions should be made in appropriate buffered solutions.
储存条件
-20°C储存,避免反复冻融
运输条件
超低温运输
稳定性与储存
-20℃保存 12个月;复溶后建议分装,避免反复冻融。
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Recombinant Human CD28 Protein (rp231841) - ELISA
Immobilized Recombinant Human CD28 Protein (rp231841) at 1.0 μg/mL can bind Theralizumab (anti-CD28) (Ab190136) with the EC₅₀ of 249.3 ng/mL.
Recombinant Human CD28 Protein (rp231841) - SDS-PAGE
3 μg/lane of Recombinant Human CD28 Protein was resolved with SDS-PAGE under reducing (R) conditions and visualized by Coomassie® Blue staining, showing a band at 50.0-63.1 kDa under reducing conditions.