P-selectin

**Figure 3:** Schematic representation of life cycle of P-selectin. It is manufactured and stored in the Weibel-Palade body in endothelial cells (it is also found in $\alpha$ granules in platelets). Stimulation by hypoxia, free radicals, histamine and thrombin results in expression of P-selectin on the surface of the endothelial cell. The main ligand of P-selectin appears to be sialated Lewis on Leucocytes. It may also bind with L-selectin on leucocytes.
$\begin{figure}\par\centering\par \includegraphics{p-selectin} \par\index{P-selectin!Life cycle} \index{Weibel-Palade body}\par\end{figure}$

P-selectin (CD62P, also called as GMP-140 or PADGEM) is a glycoprotein stored in $\alpha$ granules of platelets and Weibel-Palade bodies of endothelial cells. The expression of P-selectin can be up-regulated by thrombin, histamine and peroxides, and rapidly moved to the cell surface, reaching peak levels of expression within 3 to 10 minutes and decreasing to negligible levels by 30 minutes (thrombin and histamine) to 3 hours (oxidants) during inflammatory response and tissue injury [McE91]. It is now known that leucocyte rolling is modulated by P-selectin. This has been demonstrated by immunoneutralization with P-selectin monoclonal antibodies and P-selectin ``knockout'' mice.