Receptor dimerisation is key event in PDGF receptor activation. The intracellular regions 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 (PDGFRB) is important for activation of the kinase. This tyrosine is conserved in the alpha-receptor (PDGFRA), where it corresponsds to 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; of the 15( beta) or 16 (alpha) tyrosine residues in the intracellular, non-catalytic part of the beta- or alpha receptor, 11 and 10, respectively, are autophosphorylation sites (reviewed in Heldin et al, 1998).
PDGFRA and PDGFRB activity can be inhibited by binding to type I and type II tyrosine kinase inhibitors (reviewed in Roskoski, 2018). Type I inhibitors such as crenolanib, avripatinib and pazopanib, bind to the active conformation of the receptor and inhibit trans-autophosphorylation (Ip et al, 2018; Evans et al, 2017; Davids et al, 2009; reviewed in Roskoski, 2018; Klug et al, 2018; Papadopoulos and Lennartsson, 2016).