Activation of platelets by vessel wall collagens

Platelets interact directly with collagens of the blood vessel wall through the integrin alpha2beta1 and the Ig superfamily receptor, glycoprotein (Gp) VI. Recognition motifs within the collagens for each receptor are becoming clarified, GER motifs for the integrin and GPO triplets for GpVI. Matching of recognition motifs with the receptors using specific ligands allows signalling mechanisms to be deduced. The integrin interacts with collagen in a divalent cation-dependent manner, whereas GpVI function appears cation-independent. Increased affinity of alpha2beta1 results from treatment of platelets with various agonists including ADP and ligands which recognise GpVI. The role of such activation in platelet deposition on collagen from flowing blood remains the subject of debate. Some topics, asterisked, are reviewed in [1] but not cited specifically.