PSGL-1 （P-Selectin glycoprotein ligand，also designated CD162），exists as a disulfide-linked homodimer. PSGL-1 is a type 1 membrane protein that localizes on the tips of microvilli of leukocytes. Its extracellular domain is rich in serines，threonines and prolines，and includes a series of 15 and 16 decameric repeats in HL-60 and U-937 cells，and human leukocytes，respectively. Although PSGL-1 appears to be the sole receptor for P-Selectin on human hematopoietic cells，it also interacts with E-Selectin through a unique binding site. In order to bind PSGL-1 to either E-Selectin or P-Selectin，PSGL-1 must be sialylated and fucosylated. PSLG-1 is a mucin-like molecule，much like leukosialin （CD43），CD164 and CD34. These proteins belong to an emerging family of cell adhesion receptors called sialomucins，which transduce negative signals in hematopoietic cells.
