Biochemistry of Normal Platelet Function

Resting platelets exhibit a discoid shape in the circulation. This shape is maintained by the presence of circumferential coils of microtubules arranged just beneath the surface membrane. Upon platelet activation, however, microtubules de-polymerize and platelets change their shape to spheres with spiny pseudopodia containing actin filaments. 

Glycoprotein receptors on the platelet membrane mediate the adhesion of platelets to damaged blood vessels. The interaction of platelets with von Willebrand 

The most abundant member of the platelet beta 3 integrin family is also 

Platelets also express adhesion receptors of the selectin gene family (P-selectin) and of the immunoglobulin gene superfamily (PECAM-1 and ICAM-2) (6). Expression of PECAM-1 and ICAM-2 may play a role in platelet interactions with endothelial cells and leukocytes, respectively. 

The selectins are a family of vascular cell surface receptors that are characterized by lectin-like domains at their amino termini, an adjacent epidermal growth factorlike domain, followed by multiple, short consensus repeat units homologous to those of the complement regulatory proteins. Platelet express P-selectin (CD62  

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