A SLe(x)-type proteoglycan, which through high affinity, calcium-dependent interactions with E-, P- and L-selectins, mediates rapid rolling of leukocytes over vascular surfaces during the initial steps in inflammation. Critical for the initial leukocyte capture. (Microbial infection) Acts as a receptor for enterovirus 71. Homodimer; disulfide-linked. Interaction 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. Sulfation on Tyr-51 of PSGL1 is most important for high affinity L-selectin/SELL binding while P-selectin/SELP requires sulfation on Tyr-48. E-selectin/SELE binds with much lower affinity and requires the sLe(x) epitope, but apparently not tyrosine sulfation. Dimerization appears not to be required for P-selectin/SELP binding. Interacts with SNX20. Interacts with MSN and SYK; mediates the activation of SYK by SELPLG. Interacts with HAVCR1 (PubMed:24703780). (Microbial infection) Interacts with enterovirus 71 capsid proteins. (Microbial infection) Interacts with Staphylococcus aureus proteins SSL5 and SSL11; these interactions prevent SELPLG-mediated neutrophil rolling. Expressed on neutrophils, monocytes and most lymphocytes. Displays complex, core-2, sialylated and fucosylated O-linked oligosaccharides, at least some of which appear to contain poly-N-acetyllactosamine with varying degrees of substitution. Mainly disialylated or neutral forms of the core-2 tetrasaccharide, Galbeta1-->4GlcNAcbeta1-->6(Galbeta1-->3)GalNAcOH. The GlcN:GalN ratio is approximately 2:1 and the Man:Fuc ratio 3:5. Contains about 14% fucose with alpha-1,3 linkage present in two forms: One species is a disialylated, monofucosylated glycan, and the other, a monosialylated, trifucosylated glycan with a polylactosamine backbone. The fucosylated forms carry the Lewis antigen and are important for interaction with selectins and for functioning in leukocyte rolling. The modification containing the sialyl Lewis X glycan is on Thr-57. No sulfated O-glycans. Some N-glycosylation. Sulfation, in conjunction with the SLe(x)-containing glycan, is necessary for P- and L-selectin binding. High affinity P-selectin binding has a preferred requirement for the isomer sulfated on both Tyr-48 and Tyr-51, whereas L-selectin binding requires predominantly sulfation on Tyr-51 with sulfation on Tyr-48 playing only a minor role. These sulfations play an important role in L- and P-selectin-mediated neutrophil recruitment, and leukocyte rolling. P-selectin glycoprotein ligand 1 entry