Figure 6.

The Proposed Mechanism Depicting Roles of CTD and CTE in the Formation of Mammalian Translation Initiation Complex

(A) IF3_mt binds to the 28S subunit, with its CTE in an extended position, as observed in our structure.

(B) If the mRNA is present, as probed by the conserved lysine residues in CTD of IF3_mt, the position of CTE (green) changes to accommodate binding of the IF2_mt·fMet-tRNA_i·GTP complex.

(C) 28S initiation complex formed.

(D and E) (D) If the mRNA is absent, the CTE (green) remains in an extended position to (E) sterically block the binding of the IF2_mt·fMet-tRNA_i·GTP complex.