Recombinant Human/Cynomolgus/Rhesus CD28 Fc Avi-tag, CF

When Recombinant Human B7-1/CD80 Fc Chimera Protein (Catalog # 10133-B1) is immobilized at 10 μg/mL (100 μL/well), the concentration of Biotinylated Recombinant Cynomolgus Monkey/Rhesus Macaque CD28 Fc Chimera Avi-tag that produces a 50% optimal binding response is found to be 0.5-3 μg/mL.

• Reactivity: Hu, Pm-Cm, RM
• Applications: Bioactivity
• Format: Carrier-Free

Recombinant Human/Cynomolgus/Rhesus CD28 Fc Avi-tag, CF Summary

• Additional Information: Biotinylated
• Details of Functionality: Measured by its binding ability in a functional ELISA. When Recombinant Human B7-1/CD80 Fc Chimera Protein (Catalog # 10133-B1) is immobilized at 10 µg/mL (100 µL/well), the concentration of Biotinylated Recombinant Cynomolgus Monkey/Rhesus Macaque CD28 Fc Chimera Avi-tag that produces a 50% optimal binding response is found to be 0.5-3 µg/mL.
• Source: Chinese Hamster Ovary cell line, CHO-derived CD28 protein
  

  Human/Cynomolgus Monkey/Rhesus Macaque CD28 (Asn19-Pro152) Accession # P10747.1	DMD	Human IgG1 (Pro100-Lys330)	Avi-tag
  N-terminus			C-terminus

• Accession #: P10747.1
• N-terminal Sequence: Asn19
• Structure / Form: Disulfide-linked homodimer, biotinylated via Avi-tag
• Protein/Peptide Type: Recombinant Proteins
• Purity: >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.
• Endotoxin Note: <0.10 EU per 1 μg of the protein by the LAL method.

Applications/Dilutions

• Dilutions:
  • Bioactivity
• Theoretical MW: 42 kDa (monomer).
  Disclaimer note: The observed molecular weight of the protein may vary from the listed predicted molecular weight due to post translational modifications, post translation cleavages, relative charges, and other experimental factors.
• SDS-PAGE: 120-140 kDa, under non-reducing conditions

Packaging, Storage & Formulations

• Storage: Use a manual defrost freezer and avoid repeated freeze-thaw cycles.
• Buffer: Supplied as a 0.2 μm filtered solution in PBS.
• Purity: >95%, by SDS-PAGE visualized with Silver Staining and quantitative densitometry by Coomassie® Blue Staining.

Notes

This product is produced by and ships from R&D Systems, Inc., a Bio-Techne brand.

Alternate Names for Recombinant Human/Cynomolgus/Rhesus CD28 Fc Avi-tag, CF

• CD28 antigen (Tp44)
• CD28 antigen
• CD28 molecule
• CD28
• MGC138290
• T-cell-specific surface glycoprotein CD28
• Tp44

Background

CD28 is the founding member of a subfamily of structurally homologous costimulatory or immune checkpoint molecules of the immunoglobulin (Ig) superfamily. The CD28/B7 pathway has been shown to play a central role in immune responses against infection, autoimmune diseases, and graft rejection (1). CD28 subfamily members, including ICOS, CTLA4, PD1, PD1H, and BTLA, are characterized by a single Ig V-like extracellular domain (ECD), a transmembrane domain and an intracellular domain with highly conserved tyrosine-based signaling motifs (2). CD28 and ICOS predominately enhance T-cell activation, while CTLA-4, PD-1 and BTLA are inhibitory (1-3).  The mature ECD of human CD28 shares 65% and 66% amino acid sequence identity with mouse and rat CD28, respectively. 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 is expressed on approximately 80% of CD4+ T cells and 50% of CD8+ T cells in humans, with the proportion of CD28-positive T cells declining with age (1-4). CD28 expression has been identified on other cell lineages, including bone marrow stromal cells, plasma cells, neutrophils, and eosinophils (5). CD28 is expressed on the cell surface as a disulfide-linked homodimer and the covalent bond is required for maximum activity (6,7). 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. While, CD28 ligation is critical in promoting proliferation and effector function of conventional T cells, it also promotes the anti-inflammatory function of Treg cells. Thus, CD28 serves both pro- and anti-inflammatory roles depending on the cell type and context in which it is expressed (8). The CD28 pathway has effects both at amplifying signals initiated by the T cell receptor and on a variety of processes, including signaling, metabolism, transcription, epigenetic modifications, post-translational modifications, and RNA splicing (9).Our Avi-tag Biotinylated CD28 features biotinylation at a single site contained within the Avi-tag, a unique 15 amino acid peptide.  Protein orientation will be uniform when bound to streptavidin-coated surface due to the precise control of biotinylation and the rest of the protein is unchanged so there is no interference in the protein's bioactivity.

1. Sandigursky, S. et al. (2020). Clin Immunol. 217:108485l.
2. Chen, L. and Flies D.B. (2013) Nat Rev Immunol. 13:227.
3. Esensten, J.H. et al. (2016) Immunity. 44:973.
4. Jonathan, H. et al. (2016) Immunity. 44:937.
5. Boomer, J.S. and Green, J.M. (2010) Cold Spring Harb Perspect Biol 2:a002436.
6. Greene, J.L. et al. (1996) J Biol Chem. 271:26762.
7. Lazar-Molnar, E. et al. (2006) Cell Immunol. 244:125.
8. He, X. et al. (2017) Scientific Reports. 7:43003.
9. West, S.M. et al. (2019) Exp Biol. Med. (Maywood) 244:1577.

Bioinformatics

• Uniprot:
  • P10747.1()