is a cell adhesion molecule
) found in granules in endothelial
cells (cells lining blood vessels) and activated platelets
. Other names for P-selectin include CD62P, Granule Membrane Protein 140 (GMP-140), and Platelet Activation-Dependent Granule to External Membrane Protein (PADGEM). It was first shown to be found in endothelial cells in 1989.
P-selectin plays an essential role in the initial recruitment of leukocytes
(white blood cells
) to the site of injury during inflammation
. When endothelial cells are activated by molecules such as histamine or thrombin during inflammation, P-selectin moves from an internal cell location to the endothelial cell surface.
Thrombin is one trigger which can stimulate endothelial-cell release of P-selectin and recent studies suggest an additional Ca2+-independent pathway involved in release of P-selectin.
Ligands for P-selectin on eosinophils and neutrophils are similar sialylated, protease-sensitive, endo-beta-galactosidase-resistant structures, clearly different than those reported for E-selectin, and suggest disparate roles for P-selectin and E-selectin during recruitment during inflammatory responses.
: stored in the membrane of Weibel-Palade bodies
Platelets: stored in alpha-granules.