Binding of Epo to its homodimeric receptor and initiation of signal transduction. (A) Crystal structure of the complex of Epo with 2 extracellular domains of EpoR (from Syed et al).¹¹  Red cylinders denote α-helices and green ribbons denote β-sheets. For detailed information on interacting sites in the complex see Syed et al.¹¹  (B) Schematic representation of the conformational change imposed on the dimeric Epo receptor (EpoR) upon binding to Epo. The close proximity off the cytosolic domains of the dimeric EpoR enables autophosphorylation of JAK2 and the initiation of signal transduction. Modified from Remy et al.¹³