L-selectin
L-selectin, also known as CD62L, is a cell adhesion molecule found on leukocytes and the preimplantation embryo. It belongs to the selectin family of proteins, which recognize sialylated carbohydrate groups. It is cleaved by ADAM17.

CD62L is a cell surface component that is a member of a family of adhesion/homing receptors that play important roles in lymphocyte-endothelial cell interactions. The molecule is composed of multiple domains: one homologous to lectins, one to epidermal growth factor, and two to the consensus repeat units found in C3/C4-binding proteins.

Ligands 
GlyCAM-1, found in the high endothelial venules of the lymph nodes.
CD34, found on endothelial cells.
MadCAM-1, found on endothelial cells of gut-associated lymphoid tissue.
PSGL-1, binds with low affinity.

Function 
L-selectin acts as a "homing receptor" for lymphocytes to enter secondary lymphoid tissues via high endothelial venules. Ligands present on endothelial cells will bind to lymphocytes expressing L-selectin, slowing lymphocyte trafficking through the blood, and facilitating entry into a secondary lymphoid organ at that point. The receptor is commonly found on the cell surfaces of T cells.  Naive T-lymphocytes, which have not yet encountered their specific antigen, need to enter secondary lymph nodes to encounter their antigen.  Central memory T-lymphocytes, which have encountered antigen, express L-selectin to localize in secondary lymphoid organs.  Here they reside ready to proliferate upon re-encountering antigen.  Effector memory T-lymphocytes do not express L-selectin, as they circulate in the periphery and have immediate effector functions upon encountering antigen.

High expression of L-selectin on human bone marrow progenitor cells is an early sign of cells becoming committed to lymphoid differentiation.

L-selectin is also present on the surface of human embryo trophoblasts prior to implantation into the uterus.  Similar to its function in lymphocytes, L-selectin acts as a receptor to facilitate adhesion of the embryo to the site of invasion on the surface epithelium of the uterine endometrium.  The embryo secretes human chorionic gonadotropin (hCG), which downregulates anti-adhesion factor, MUC-1, located on the uterine epithelium at the site of invasion.  Removal of MUC-1 exposes the oligosaccharide ligands of the uterine epithelium, thus allowing binding by the L-selectin receptor of the trophopblast cell, followed by embryo adhesion and invasion.