Fig. 5.
ITAM and integrin receptors on platelets. GPVI, FcγIIa, and CLEC-2 belong to a class of hemi(ITAM) receptors that are involved in platelet activation. Whereas GPVI and α2β1 are activated by collagen, FcγIIa recognizes IgG immune complexes to induce integrin αIIbβ3 activation. CLEC-2 contains a single YxxL motif that is activated by podoplanin. Ligand binding to GPVI or FcγIIa results in Syk and subsequent PLCγ2 activation, leading to platelet aggregation, mediated by the active conformation of integrin αIIbβ3.