Structure and mechanism of activity-based inhibition of the EGF-Receptor by Mig6

Mig6 is a feedback inhibitor that directly binds, inhibits and drives internalization of ErbB-family receptors. Mig6 selectivity targets activated receptors. Here we find that the EGF receptor phosphorylates Mig6 on Tyr394, and that this phosphorylation is primed by prior phosphorylation of an adjacent residue, Tyr395, by Src. Crystal structures of human EGFR–Mig6 complexes reveal the structural basis for enhanced phosphorylation of primed Mig6 and show how Mig6 rearranges after phosphorylation by EGFR to effectively irreversibly inhibit the same receptor that catalyzed its phosphorylation. This dual phosphorylation site allows Mig6 to inactivate EGFR in a manner that requires activation of the target receptor and can be modulated by Src. Loss of Mig6 is a driving event in human cancer; analysis of 1057 gliomas reveals frequent focal deletions of ERRFI, the gene that encodes Mig6, in EGFR-amplified glioblastomas.