Recombinant Human PD-L1/B7-H1 His-tag Avi-tag Protein, CF Summary
Accession # Q9NZQ7
CF stands for Carrier Free (CF). We typically add Bovine Serum Albumin (BSA) as a carrier protein to our recombinant proteins. Adding a carrier protein enhances protein stability, increases shelf-life, and allows the recombinant protein to be stored at a more dilute concentration. The carrier free version does not contain BSA.
In general, we advise purchasing the recombinant protein with BSA for use in cell or tissue culture, or as an ELISA standard. In contrast, the carrier free protein is recommended for applications, in which the presence of BSA could interfere.
|Formulation||Lyophilized from a 0.2 μm filtered solution in PBS with Trehalose.|
|Reconstitution||Reconstitute at 500 μg/mL in PBS.|
|Shipping||The product is shipped at ambient temperature. Upon receipt, store it immediately at the temperature recommended below.|
|Stability & Storage:||Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
When Recombinant Human PD-1 Fc Chimera (Catalog # 1086-PD) is immobilized at 2 µg/mL, Biotinylated Recombinant Human PD-L1 His-tag Avi-tag protein binds with an ED50of 2-12 µg/mL.
In a functional flow cytometry test, (A) Recombinant Human PD-L1/B7-H1 His-tag Avi-tag Protein (Catalog # AVI9049) binds to HEK293 human embryonic kidney cell line transfected with recombinant human PD-1 and EGFP. Ligand binding was detected by staining cells with APC-conjugated Streptavidin (Catalog # F0050), which does not stain the cells in the absence of recombinant protein (B).
2 μg/lane of Biotinylated Recombinant Human PD-L1/B7-H1 His Tag Avi Tag was resolved with SDS-PAGE under reducing (R) and non-reducing (NR) conditions and visualized by Coomassie® Blue staining, showing bands at 35-41 kDa.
B7-H1, also known as PD-L1 and CD274, is an approximately 65-kDa transmembrane glycoprotein in the B7 family of immune regulatory molecules (1). Mature human B7-H1 consists of a 220 amino acid (aa) extracellular domain (ECD) with two immunoglobulin-like domains, a 21 aa transmembrane segment, and a 31 aa cytoplasmic domain (2). Within the ECD, human B7-H1 shares 73% and 74% aa sequence identity with mouse and rat B7-H1, respectively. Alternative splicing generates additional isoforms that either lack the first Ig-like domain or are truncated within the second Ig-like domain (3). B7-H1 is expressed on inflammatory-activated immune cells including macrophages, T cells, and B cells (4-7), keratinocytes (8, 9), endothelial and intestinal epithelial cells (8, 10), as well as a variety of carcinomas and melanoma (11, 12). B7-H1 binds to T cell B7-1/CD80 and PD-1 (7, 8, 12-15). It suppresses T cell activation and proliferation (5, 8, 14, 16) and induces the apoptosis of activated T cells (11). It plays a role in the development of immune tolerance by promoting T cell anergy (7, 14) and enhancing regulatory T cell development (16). B7-H1 favors the development of anti-inflammatory IL-10 and IL-22 producing dendritic cells (5, 10) and inhibits the development of Th17 cells (16). In cancer, B7-H1 provides resistance to T cell mediated lysis, enhances EMT, and enhances the tumorigenic function of Th22 cells (6, 9, 12, 15).
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The vial is supposed to contain lyophilized protein but it appears to be empty. Is there anything in it?
Pellets can be dislodged during shipping and become disbursed on the vial wall and in the cap. Centrifuge or tap the vial on the benchtop to return this material to the vial bottom. If this does not reveal a pellet, closely inspect the cone of the vial. Some pellets appear as only a tiny amount of material or as a transparent film due to the original buffer formulation. This is a normal appearance for many proteins. For example, if the product is originally lyophilized from a solvent such as acetonitrile or ethanol, and supplied carrier-free, you may not be able to detect the pellet with the naked eye. This does not mean the vial is empty. Reconstitute the vial as directed. After reconstitution, protein concentration can be tested with a spectrophotometer.
What is the recommended method for reconstitution of a lyophilized protein or antibody?
Unless more specific directions are on the Certificate of Analysis provided with the product, we suggest the following procedure to ensure optimal recovery: 1. Allow the vial and reconstitution buffer to equilibrate to room temperature. 2. Briefly centrifuge the vial to ensure that all lyophiliate is collected at the bottom of the vial. 3. Add the amount of buffer required to achieve the concentration recommended on the product insert. 4. Allow the vial to reconstitute for 15-30 minutes at room temperature with gentle agitation, like on a rocker platform or rotating by hand. Avoid vigorous shaking that can cause foaming and protein denaturation. 5. Aliquot into volumes greater than 20 μL and store as indicated on the product insert. If the vial exhibits flakes or particulates, mix the product for a couple of hours at room temperature and then at 4oC overnight. Contact Technical Service if product does not go into solution.
Are R&D Systems recombinant proteins and antibodies sterile?
Although the vials are bottled using aseptic techniques, heat-treated vials, and sterile stock solutions, they are not considered or guaranteed to be sterile. If sterile material is needed for an experiment, the material can be filtered through a 0.2 micron filter designed for use with biological fluids.
Supplemental Cell Selection Products
Supplemental ELISA Products
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