Active Recombinant Human CTLA4 protein, Fc/Avi-tagged, Biotinylated

Specification :
| Description : CTLA-4 (cytotoxic T-lymphocyte associated protein-4, designated CD152), is a type I transmembrane T cell inhibitory molecule that is a member of the Igsuperfamily (1, 2). Human or mouse CTLA-4 cDNA encodes 223 amino acids (aa) including a 35 aa signal sequence, a 126 aa extracellular domain (ECD) with one Ig_x005f_x0002_like V-type domain, a 21 aa transmembrane (TM) sequence, and a 41 aa cytoplasmic sequence. It is found as a covalent homodimer of 41-43 kDa (2) Within theECD, human CTLA-4 shares 68%, 71% and 83-86% aa sequence identity with mouse, rat and porcine/bovine/rabbit/feline/canine CTLA-4, respectively. A 174 aa formthat lacks TM and cytoplasmic sequences (sCTLA-4) is possibly secreted (3-5). Isoforms of 56-79 aa that mainly contain parts of the cytoplasmic domain arereported. In mouse, an isoform lacking the Ig-like domain has ligand-independent inhibitory activity and is termed liCTLA-4 (6). CD28, which is structurally related toCTLA-4, is constitutively expressed on naïve T cells and promotes T cell activation when engaged by B7-2 on antigen-presenting cells (APC) within the immunologicalsynapse (IS) (1, 7, 8). In contrast, CTLA-4 is recruited from intracellular vesicles to the IS beginning 1-2 days after T cell activation (2, 7, 8). It forms a linear latticewith B7-1 on APC, inducing negative regulatory signals and ending T cell activation (9). Abatacept, a therapeutic human CTLA-4-Ig fusion protein (trade name Orencia),competes with CD28 for B7-1 and B7-2 binding and has been used to antagonize T cell activation in autoimmune conditions and to enhance transplant survival (10).Mice deleted for CTLA-4 show no abnormalities until after birth, but then develop lethal autoimmune reactions due to continued T cell activation and poor control byregulatory T cells, which constitutively express CTLA-4 in wild-type mice and humans (11-13). | Source : HEK293 cells | Species : Human | Tag : Fc/Avi | Predicted N Terminal : Ala37 | Form : Lyophilized from a 0.2 μm filtered solution in PBS with Trehalose. | Bio-activity : Measured by its binding ability in a functional ELISA. When Recombinant Human CD80 Fc Chimera is immobilized at 0.5 µg/mL (100 µL/well), Biotinylated Recombinant Human CTLA4 Fc Chimera Avi-tag binds with an ED50 of 0.4-2.4 ng/mL. | Molecular Mass : 53-61 kDa, under reducing conditions | Protein length : Ala37-Phe162 | Endotoxin : | Purity : >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining. | Applications : Bioactivity | Storage : Use a manual defrost freezer and avoid repeated freeze-thaw cycles.12 months from date of receipt, -20 to -70 °C as supplied.1 month, 2 to 8 °C under sterile conditions after reconstitution.3 months, -20 to -70 °C under sterile conditions after reconstitution. | Reconstitution : Reconstitute at 500 μg/mL in PBS.