P-selectin glycoprotein ligand 1 (PSGL-1) is also known as Selectin P ligand (SELPLG), CD antigen CD162. PSGL-1 is disulfide-linked homodimer which is the high affinitycounter-receptor for P-selectin on expressed on activated endothelial cells and platelets. PSGL-1 / SELPLG interacts with P-, E- and L-selectins, through their lectin/EGF domains, is required for promoting recruitment and rolling of leukocytes. These interactions require sialyl Lewis X glycan modification but there is a differing dependence for tyrosine sulfations. Dimerization appears not to be required for P-selectin/SELP binding. PSGL-1 can interact with SNX20, MSN and SYK. PSGL-1 / SELPLG mediate the activation of SYK by SELPLG.