Fig. 1

Schematic representation of the structural changes and activation of ErbB/HER receptors. This family is compromised by four members. Each member is composed of an extracellular region, a transmembrane region, and an intracellular region. The extracellular region, in turn, is composed of four subdomains (I-IV). The intracellular region contains the juxtamembrane domain, the tyrosine kinase domain, and the C-terminal tail with phosphorylatable residues. When the ligand binds to subdomains I and III, a conformational change is induced in the extracellular domain, leaving the dimerization arm exposed. Thanks to this, the receptor can dimerize with another member of the family in open conformation (heterodimerization) or another identical receptor (homodimerization)