P-selectin glycoprotein ligand-1 (PSGL-1), also known as SELPLG or CD162, is the high affinitycounter-receptor for P-selectin on expressed on activated endothelial cells and platelets. PSGL-1 is a mucin-type glycoprotein, expressed on leukocytes and platelets as a homodimer of two disulfide-linked subunits of ~120 kD. As cell adhesion molecules, multiple studies have shown that PSGL-1/ P-selectin interaction is required for the normal recruitment of leukocytes during inflammatory reactions, and also participates in hemostatic responses. PSGL-1 protein requires two distinct posttranslational modifications for the Ca2+-dependent recognition by the lectin domain of P-selectin, that is tyrosine sulfation and specific O-linked glycosylation (sialic acid and fucose). PSGL-1 can also bind to other two members of the selectin family, E-selectin (endothelial) and L-selectin (leukocyte), but binds best to P-selectin.