Interactions of PSGL-1 with P-selectin. (A) Structure of the P-selectin complex with the PSGL-1 ligand containing tyrosine O-sulfates and the sLe^x hexasaccharide. The P-selectin surface is color coded according to electrostatic potential (acidic region, blue; basic region, red). In addition, individual sugars in the sLe^x are color coded (Neu5Ac, purple; Gal and GalNAc, yellow; GlcNAc, blue; and Fuc, red) and the sulfur and oxygen atoms within the sulfate groups are yellow and red, respectively. (B) Interaction map of specific carbohydrate and peptide functional groups with amino acids in the P-selectin binding domain (adapted with permission from Sladek et al,³¹ Copyright 2024, American Chemical Society).