Figure 1. eEF2-dependent association of eRF1 and eRF1/eRF3 with 80S ribosomal complexes assembled on CrPV-STOP mRNA.

(A) Secondary structure of the CrPV IRES with the first Ala codon mutated to an UAA stop codon (in red). Blue circles indicate the positions of toe-prints (panel B) caused by the contacts of the IRES with the 40S and 60S ribosomal subunits. (B) Toe-printing analysis of binding of eRF1 and eRF3 to 80S ribosomal complexes assembled on CrPV-STOP mRNA, depending on the presence of eEF2. Toe-prints corresponding to the pre-translocated ribosomal complexes (+14–15 nts from the CCU codon) are indicated by a black arrow. Toe-prints corresponding to the eRF1- or eRF1/eRF3-associated post-translocated ribosomal complexes (+18–19 nts from the CCU codon) are indicated by a red arrow. The +4 nt toe-print shift in post-translocated complexes includes the +2nt shift due to the presence of eRF1 (Alkalaeva et al., 2006). Additional toe-prints caused by the contacts of the IRES with the 40S subunit (at AA₆₁₆₁–₆₁₆₂) and with the 60S subunit (U₆₂₁₇ and G₆₁₈₃) are consistent with previous reports (Wilson et al., 2000b; Hellen and Pestova, 2003) and are shown in blue.