Multiple alignment of known Sec tRNAs and/or Sec tRNA genes. (A) Sequences from eukaryotes. Animal Sec tRNAs[Ser]Sec were aligned with C. reinhardtii Sec tRNA[Ser]Sec based on secondary structure (see cloverleaf model in Fig. 2A). The sources of animal Sec tRNA[Ser]Sec sequences are summarized elsewhere (for review, see Hatfield et al. 1999). (B) Sequences from C. reinhardtii, archaea, and bacteria. Prokaryotic Sec tRNAs were aligned with C. reinhardtii Sec tRNA[Ser]Sec based on secondary structure (see above). Sources of prokaryotic sequences are given in the legend to Figure 4. The Sec anticodon of each tRNA is shown in italics. Base positions shown with a black background indicate conserved sites, those in an intermediate background, a single evolutionary change, those in a light background, two evolutionary changes, and those not shaded, more than two evolutionary changes.
