Receptor dimerisation is key event in PDGF receptor activation. The intracellular parts of the receptors are juxtaposed which allows trans-phosphorylation between the two receptors in the complex.
The autophosphorylation site Y857 located inside the kinase domain of beta-receptor is important for activation of the kinase. This tyrosine is conserved in the alpha-receptor (Y849 ) and in almost all other tyrosine kinase receptors. The other known autophosphorylation sites are localized outside the kinase domains of the alpha- and beta- receptors ; 11 out of 15 tyrosine residues in the intracellular, non-catalytic part of the beta-receptor are autophosphorylation sites