The SK3 antibody reacts with human CD4, a 59 kDa protein which acts as a co-receptor for the T cell receptor (TCR) in its interaction with MHC Class II molecules on antigen-presenting cells. The extracellular domain of CD4 binds to the beta-2 domain of MHC Class II, while its cytoplasmic tail provides a binding site for the tyrosine kinase lck, facilitating the signaling cascade that initiates T cell activation. CD4, and co-receptors CCR5 and CXCR4, may also be utilized by HIV-1 to enter T cells. Human CD4 is typically expressed on thymocytes, some mature T cell populations such as Th17 and T regulatory (Treg) cells, as well as on dendritic cells.
The SK3 antibody is widely used as a phenotypic marker for human CD4 expression, and has been reported to be cross-reactive with Rhesus and Cynomolgus CD4. This antibody does not block binding of alternative clone RPA-T4, suggesting that they recognize different epitopes.
||PerCP-Cyanine5.5 Anti-Human CD4 (SK3)
||Mouse IgG1, kappa
||Evans RL, Wall DW, Platsoucas CD, Siegal FP, Fikrig SM, Testa CM and Good RA. 1981. Proc Natl Acad Sci U S A. 78(1): 544-548.
Sattentau QJ, Dalgleish AG, Weiss RA and Beverley PC. 1986. Science. 234(4780): 1120-1123.
Bernard A, Boumsell L and Hill C. In: Bernard A, Boumsell L, Dausset J, Milstein C, Schlossman SF, ed. Leucocyte Typing. New York, NY: Springer-Verlag; 1984: 9-108. (Flow Cytometry)
Heninger AK, Theil A, Wilhelm C, Petzold C, Huebel N, Kretschmer K, Bonifacio E and Monti P. 2012. J Immunol. 189(12): 5649-5648. (Flow Cytometry)
Yoshino N, Ami Y, Terao K, Tashiro F and Honda M. 2000. Exp. Anim. 49(2): 97-110. (Flow Cytometry – Cynomolgus)
Lafont BAP, Gloeckler L, D’Hautcourt JL, Gut JP and Aubertin AM. 2000. Cytometry 41: 193-202. (Flow Cytometry – Rhesus)
Application Key:FC = Flow Cytometry; FA = Functional Assays; ELISA = Enzyme-Linked Immunosorbent Assay; ICC = Immunocytochemistry; IF = Immunofluorescence Microscopy; IHC = Immunohistochemistry; IHC-F = Immunohistochemistry, Frozen Tissue; IHC-P = Immunohistochemistry, Paraffin-Embedded Tissue; IP = Immunoprecipitation; WB = Western Blot; EM = Electron Microscopy
*Tonbo Biosciences tests all antibodies by flow cytometry. Citations are provided as a resource for additional applications that have not been validated by Tonbo Biosciences. Please choose the appropriate format for each application and consult the Materials and Methods section for additional details about the use of any product in these publications.
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