Recombinant Human CD5 Protein, CF

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R&D Systems Recombinant Proteins and Enzymes
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Recombinant Human CD5 Protein, CF Summary

Product Specifications

>95%, by SDS-PAGE under reducing conditions and visualized by silver stain
Endotoxin Level
<0.10 EU per 1 μg of the protein by the LAL method.
Measured by its binding ability in a functional ELISA. When Zymosan is coated at 200 μg/mL (100 μL/well), the concentration of Recombinant Human CD5 that produces 50% optimal binding response is typically 0.6-3 μg/mL.
Mouse myeloma cell line, NS0-derived human CD5 protein
Arg25-Asn371, with a C-terminal 10-His tag
Accession #
N-terminal Sequence
Structure / Form
Predicted Molecular Mass
39.9 kDa
55 kDa, reducing conditions

Product Datasheets

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Carrier Free

What does CF mean?

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.

What formulation is right for me?

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.
Reconstitution Reconstitute at 100 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.
  • 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 Calculator

Reconstitution Calculator

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Background: CD5

CD5, also known as Leu-1, Ly-1, and T1, is a 67 kDa transmembrane glycoprotein in the scavenger receptor superfamily (1). Mature human CD5 consists of a 348 amino acid (aa) extracellular domain (ECD) with three scavenger receptor cysteine-rich (SRCR) domains, a 30 aa transmembrane segment, and a 93 aa cytoplasmic domain (2). Within the ECD, human CD5 shares 55% aa sequence identity with mouse and rat CD5. The 52 kDa ECD can be cleaved from the cell surface and circulates in the serum (3). CD5 has been shown to interact homophilically, with CD72 on B cells, and with beta-glucan components of fungal cell walls (4‑6). CD5 expression on developing thymocytes is positively regulated by signaling through the T cell antigen receptor (TCR) and is up‑regulated on tolerized peripheral CD4+ cells (7, 8). It inhibits TCR signaling and promotes T cell nonresponsiveness and survival (8‑10). CD5 signaling inhibits the generation of regulatory T cells but promotes the development of Th17 cells (11, 12). Within the B cell lineage, CD5 is expressed on B-1a cells, anergic B cells, and IL-10 producing regulatory B cells (13‑16). Similarly to on T cells, it negatively regulates signaling through the B cell antigen receptor and supports peripheral B cell survival, anergy, and tolerance (13, 14, 16). B cells can produce an intracellularly-retained form of CD5 which lacks the signal peptide and a portion of the first SRCR domain (17). CD5 is also involved in the cellular entry of hepatitis C virus into T cells (18).

  1. Soldevila, G. et al. (2011) Curr. Opin. Immunol. 23:310.
  2. Jones, N.H. et al. (1986) Nature 323:346.
  3. Calvo, J. et al. (1999) Tissue Antigens 54:128.
  4. Brown, M.H. and E. Lacey (2010) J. Immunol. 185:6068.
  5. Van de Velde, H. et al. (1991) Nature 351:662.
  6. Vera, J. et al. (2009) Proc. Natl. Acad. Sci. 106:1506.
  7. Azzam, H.S. et al. (1998) J. Exp. Med. 188:2301.
  8. Hawiger, D. et al. (2004) Immunity 20:695.
  9. Tarakhovsky, A. et al. (1995) Science 269:535.
  10. Friedlein, G. et al. (2007) J. Immunol. 178:6821.
  11. Ordonez-Rueda, D. et al. (2009) Eur. J. Immunol. 39:2233.
  12. de Wit, J. et al. (2011) Blood 118:6107.
  13. Bikah, G. et al. (1996) Science 274:1906.
  14. Hippen, K.L. et al. (2000) J. Exp. Med. 191:883.
  15. Yanaba, K. et al. (2008) Immunity 28:639.
  16. Gary-Gouy, H. et al. (2002) Blood 100:4537.
  17. Renaudineau, Y. et al. (2005) Blood 106:2781.
  18. Sarhan, M.A. et al. (2012) J. Virol. Epub.
Entrez Gene IDs
921 (Human); 12507 (Mouse)
Alternate Names
CD5 antigen (p56-62); CD5 antigen; CD5 molecule; CD5; LEU1T-cell surface glycoprotein CD5; Lymphocyte antigen T1/Leu-1; T1

Citations for Recombinant Human CD5 Protein, CF

R&D Systems personnel manually curate a database that contains references using R&D Systems products. The data collected includes not only links to publications in PubMed, but also provides information about sample types, species, and experimental conditions.

2 Citations: Showing 1 - 2
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  1. Macrophage CD5L is a target for cancer immunotherapy
    Authors: L Sanchez-Mo, T Paul, C Martori, J Font-Díaz, L Sanjurjo, G Aran, É Téllez, J Blanco, J Carrillo, M Ito, M Tuttolomon, HJ Ditzel, C Fumagalli, G Tapia, J Sidorova, H Masnou, MA Fernández-, JJ Lozano, C Vilaplana, A Rodriguez-, C Armengol, AF Valledor, L Kremer, MR Sarrias
    EBioMedicine, 2023-04-11;91(0):104555.
    Species: Mouse
    Sample Types:
    Applications: ELISA Capture
  2. Trans-signaling of interleukin-6 (IL-6) is mediated by the soluble IL-6 receptor, but not by soluble CD5
    Authors: S Aparicio-S, M Deseke, A Lickert, C Garbers
    Biochem. Biophys. Res. Commun, 2017-01-31;0(0):.
    Applications: Bioassay


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