 Epidermal growth factor receptor

In an illustrative EGFR activation route, EGF stabilizes an associated pair of receptor chains. Asymmetric contact between their protein kinase protein domains activates one catalytic partner without requiring its activation-loop phosphorylation. Subsequent phosphorylation of cytoplasmic tails creates recruitment sites. Preassociated inactive EGFR populations can also occur: the cartoon's separated starting chains are not a universal initial condition.^[ref]