Extended Data Figure 6. Hydrogen bonds specify for uridine at the +1 position.
Chemical diagrams of uridine and cytidine with hydrogen bond donors (blue) and acceptors (magenta) indicated. Two of the three hydrogen bonds that uridine forms with Asn61 and Lys63 of the NIKS motif of eRF1AAQ (purple) are not possible with cytidine (see also Fig. 4a).