Figure 5.

Superposition of SelB domain III with the corresponding EF-Tu domain, which is involved in a tRNA backbone contact. (A) SelB (magenta) contains a loop that is considerably extended in comparison with EF-Tu (cyan), where this region is involved in tRNA (grey) binding. Contacts between SelB and the modelled tRNA^Cys are coloured in red. The base-pair numbering is according to tRNA^Cys. In addition, the corresponding bases from M. maripaludis tRNA^Sec are shown in brackets. (B) Possible contact sites of SelB with tRNA^Sec are shown in the secondary structure diagram of M. maripaludis Sec-tRNA^Sec and are coloured in red. The contact area is derived from the tRNA^Cys:SelB model. Note the prolonged 13 bp acceptor arm (labelled with a green arrow) that is formed by stacking of the 9 bp acceptor stem and the 4 bp T stem and is an important difference when compared to canonical elongator tRNAs.