FIG. 7.

Structure-function relationships with the cytokine receptor superfamily. Schema demonstrating the location of the conserved box 1, V-box, box 2, and X-box motifs (as sequentially indicated by increased shading) and tyrosine residues (indicated by Y) in various cytokine receptors. The arrow indicates the shortest C-terminal truncation that produces a mutation capable of initiating ligand-induced proliferation. Like the PRLr, an appreciable portion of the C terminus of the IL-2r β chain (IL2rβ) is necessary for the induction of cell proliferation. GHr, growth hormone receptor; EPOr, erythropoietin receptor; G-CSFr, granulocyte–colony-stimulating factor.