FIGURE 7:

Speculative model for Ded1 in the translational stress response. (A) In nonstress conditions, Ded1 stimulates translation by promoting assembly of the 48S PIC. (B) In stress, WT Ded1 may be directly involved in two steps of translation repression. First, Ded1 may stall the assembly of the 48S PIC. In a second step, Ded1 promotes the removal of eIF4G1 from stalled translation PICs, which leads to the codegradation of both factors. (C) In cellular stress ded1 mutants (ded1-120/ded1-ΔCT) are not effective in stalling 48S PIC assembly. The removal and degradation of eIF4G1 from PICs is also impaired, as this step requires Ded1 enzymatic activity and/or a functional interaction between the Ded1 C-terminus and eIF4G1. Thus, eIF4G1 is retained in translation complexes and helps sustain translational activity.