Fig. 1. Cross-linking patterns obtained with 42mer mRNA analogs containing stop codons (UAG, UAA or UAG) or a sense codon (UCA) in presence of C-terminally His-tagged human wild-type eRF1 (wt) or mutated human eRF1 containing either S64D or I35V-L126F substitutions. After irradiation, the reaction products were separated onto a 10% SDS–polyacrylamide gel and analyzed by autoradiography. A control reaction without eRF1 (No eRF1) is shown for each mRNA analog. The 68 kDa band corresponding to the eRF1–mRNA cross-link is indicated by an arrow. Molecular mass markers in kDa are indicated on the left.