Figure 2.

Selectin structure and expression. The selectin family consists of three members: E-selectin is expressed on the surface of activated endothelial cells, P-selectin occurs on endothelial cells as well as on platelets. L-selectin is expressed on leukocytes and can be shed by specific enzymes including A disintegrin and metalloproteinase 17 (ADAM17). Selectins share a common structure, characterized by an N-terminal C-type lectin domain, followed by an epidermal-growth-factor-like domain (EGF) and a number of consensus repeats, which is characteristic for each selectin. The transmembrane domain is followed by a short cytoplasmic tail. The cytoplasmic tail of L-selectin (amino acid sequence shown at the bottom) is highly conserved between species and is able to fulfill signaling function.