LAG-3 Protein, Mouse (HEK293)

LAG-3 (Lymphocyte activation gene 3) protein is an inhibitory receptor expressed on antigen-activated T-cells, delivering inhibitory signals upon binding to ligands such as FGL1. Serving as a major ligand of LAG3, FGL1 is responsible for LAG3's T-cell inhibitory function. Following T-cell receptor (TCR) engagement, LAG3 associates with CD3-TCR in the immunological synapse, directly inhibiting T-cell activation. LAG3 may synergistically inhibit antigen-specific T-cell activation with PDCD1/PD-1, possibly acting as a coreceptor for PD-1. It negatively regulates the proliferation, activation, effector function, and homeostasis of both CD8(+) and CD4(+) T-cells. Constitutively expressed on a subset of regulatory T-cells (Tregs), LAG3 contributes to their suppressive function, mediating immune tolerance. Additionally, LAG3 acts as a negative regulator of plasmacytoid dendritic cell (pDCs) activation and binds to MHC class II (MHC-II), possibly functioning as a ligand for MHC-II on antigen-presenting cells, thereby promoting APC activation/maturation and driving Th1 immune responses.