Selectin P ligand, also known as SELPLG or CD162 (cluster of differentiation 162), is a human gene.
SELPLG codes for PSGL-1, the high affinity counter-receptor for P-selectin on myeloid cells and stimulated T lymphocytes. As such, it plays a critical role in the tethering of these cells to activated platelets or endothelia expressing P-selectin. Naive and stimulated lymphocytes appear to use PSGL-1 for trafficking into and out of lymph nodes. The gene and protein structure of human PSGL-1 was first discovered in 1993. The research team at Genetics Institute (GI) named the molecule PSGL-1 for "P-selectin glycoprotein ligand-1" although it was found to also bind the other two selectins types. In 1994, the GI team now led by Gray Shaw discovered that most of the binding activity of PSGL-1 was localized within its N-terminal 19 amino acids, including three sulfotyrosines (Tys) at positions 5, 7 and 10 and a critical O-linked glycan attached to the threonine at position 16 of the mature, fully processed PSGL-1 present on a cell's surface. They termed this the "anionic segment" of PSGL-1 in 1995 and then published the co-crystal structure of human PSGL-1's anionic segment bound to human P-selectin in 2000.
The organization of the SELPLG gene closely resembles that of CD43 and the human platelet glycoprotein GpIb-alpha both of which have an intron in the 5-prime-noncoding region, a long second exon containing the complete coding region, and TATA-less promoters.
P-selectin glycoprotein ligand-1 (PSGL-1) is a dimeric mucin-like glycoprotein found primarily on the surface of white blood cells. PSGL-1 can serve as a ligand for P-selectin (P stands for platelet), which is one of a family of selectins that includes E-selectin (endothelial) and L-selectin (leukocyte). Selectins are part of the broader family of cell adhesion molecules. PSGL-1 can bind to each of the three members of the family but binds best (with the highest affinity) to P-selectin.