Figure 4.

Positive selection and critical functional sites in retroviral restriction factors and their virus gene targets. Brackets define interacting virus/host pairs. Sites of positive selection in MLVs, and in host genes, are identified by black arrows; sites identified in rodent orthologs by gray arrows; red arrows and bars mark residues or regions critical for restriction or that are restriction targets. Numbers identify residues involved in virus/host interactions that are also under positive selection. VRA, VRB, variable domains; PRR, proline rich region; ECL, extracellular loop; MHR, major homology region; n and b identify alternative C-termini of Fv1.