LAG-3 (also called CD223) is a high affinity MHC class II ligand present on the surface of CD4 CD8 T cells and NK cell, with shared homology in structure to CD4 molecules. It has a glutamic acid-proline (EP) repetitive sequence found in other functionally distinct mammalian, parasitic, and bacterial proteins that may influence a conserved biological function. LAG-3 CD4 CD8 T cells can associate with the T cell receptor (TCR) and downregulate TCR signaling in vitro. LAG-3 inhibits CD4-dependent T cell function via its cytoplasmic domain. LAG-3 Lys-468 within a conserved 'KIEELE' motif is essential for interaction with downstream signaling molecules. Furthermore, as a checkpoint inhibitor target, it may be superior to CTLA-4 and PD-1 since both antibodies only activate effector T-cells, whereas an antagonist LAG-3 antibody can both activate T effector cells (by downregulating the LAG-3 inhibiting signal into pre-activated LAG-3 cells) and inhibit induced (i. e. antigen-specific) Treg suppressive activity. Primary antibodies are available purified, or with a selection of fluorescent CF® Dyes and other labels. CF® Dyes offer exceptional brightness and photostability. Note: Conjugates of blue fluorescent dyes like CF®405S and CF®405M are not recommended for detecting low abundance targets, because blue dyes have lower fluorescence and can give higher non-specific background than other dye colors.