P-Selectin (P-Selectin, GMP-140) belongs to the family of adhesion molecules, the Selectins. P-selectin acts as a receptor that supports the attachment of leukocytes to activated platelets and endothelium. P-selectin mediates adhesion functions in conjunction with cell-cell interactions mediated by other cognate molecules and is likely to be important in both hemostatic and inflammatory processes. P-selectin molecules are located in the granule membranes of unstimulated platelets and are redistributed to the cell surface upon platelet activation. P-selectin is also found in endothelial cells in the membranes of Weibel-Palade bodies and megakaryocytes. The appearance of P-selectin at the cell surface is very rapid but also decreases shortly after stimulation to its basal level.
P-selectin's physiological role may be mediating the initial adhesion of leukocytes to activated endothelium during acute inflammation. It may work together with Selectin E to initially direct neutrophils and monocytes to specific attachment areas at sites of acute inflammation. A soluble form of Selectin P found in plasma has been described. It could represent a proteolytic fragment or, more likely, a soluble variant of the molecule lacking its transmembrane domain. Soluble P-Selectin is potentially an important molecule, and its measurement can provide information in various pathological conditions. Excessive accumulation of neutrophils on the endothelial surface accompanied by high expression of P-selectin has been implicated in several inflammatory disorders, including adult respiratory distress syndrome, acute lung injury, ischemia-reperfusion injury, septic shock from Gram-negative bacteria, thrombosis, and rheumatoid arthritis. Malignant cells were shown to express receptors for P-Selectin, suggesting an essential role of P-Selectin in tumorigenesis and metastasis.
Important Note
Selectin P is only measured for research purposes in clinical studies and experimental protocols.
