P-Selectin (SELP)

P-selectin is the largest of the known selectins at 140kDa. It contains nine consensus repeats (CR) and extends approximately 40 nm from the endothelial surface. P-selectin is expressed in a-granules of activated platelets and granules of endothelial cells. Within minutes of stimulation of the endothelial cells by inflammatory mediators such as histamine, thrombin, or phorbol esters, P-selectin is surface-expressed. Expression of P-selectin also occurs from the surgical trauma endured during preparation of the tissues for intravital microscopy. The expression is short-lived, reaching its peak after only ten minutes. Additional synthesis of P-selectin is brought about within two hours by cytokines such as interleukin-1 (IL-1) or tumor necrosis factor a (TNF-a).