Figure 5.

Schematic representation of the regulation of protein synthesis by γ₁34.5 in infected cells. As described in the text, PKR is activated after the onset of DNA synthesis in cells infected with HSV-1. In the absence of γ₁34.5, eIF-2α is phosphorylated and protein synthesis ceases. γ₁34.5 binds to PP1α and dephosphorylates eIF-2α. It is not known whether the γ₁34.5–PP1 complex is sufficient or requires additional factors to dephosphorylate eIF-2α. Because GADD34 substitutes for γ₁34.5, it is conceivable that one of the functions of GADD34 is to prevent shutoff of protein synthesis by a similar mechanism.