All selectins are single-chain transmembrane glycoproteins that share similar properties to C-type lectins due to a related amino terminus and calcium-dependent binding.

[4] Though they share common elements, their tissue distribution and binding kinetics are quite different, reflecting their divergent roles in various pathophysiological processes.

These three types share a significant degree of sequence homology among themselves (except in the transmembrane and cytoplasmic domains) and between species.

These parts of the selectin molecules are responsible for their targeting to different compartments: P-selectin to secretory granules, E-selectin to the plasma membrane, and L-selectin to the tips of microfolds on leukocytes.

Cytokines such as TNF-alpha stimulate transcription and translation of E-selectin and additional P-selectin, which account for the delay of several hours.

[7] As the leukocyte rolls along the blood vessel wall, the distal lectin-like domain of the selectin binds to certain carbohydrate groups presented on proteins (such as PSGL-1) on the leukocyte, which slows the cell and allows it to leave the blood vessel and enter the site of infection.

[2] Each selectin has a carbohydrate recognition domain that mediates binding to specific glycans on apposing cells.

In particular, genetic regulation and activation of specific chemokines, cytokines and proteases may direct metastasis to a preferred organ.

This triggers the activation of integrins from the cancer cells allowing their firmer adhesion to members of the Ig-CAM family such as ICAM, initiating the transendothelial migration and extravasation processes.

On the other hand, several studies further show that cancer cells may initiate the expression of endothelial adhesion molecules in a more indirect ways.

Selectins are involved in projects to treat osteoporosis, a disease that occurs when bone-creating cells called osteoblasts become too scarce.

Researchers have developed a way to use selectins to direct stem cells introduced into the vascular system to the bone marrow.