Comparison of bacterial and eukaryotic SECIS elements in deiodinase, GPx and SelW protein sequences. (a) In bacterial SECIS elements, only sequences downstream of in-frame UGA codons are shown and the conserved features (in-frame UGA codon and conserved G in the apical loop) are highlighted in red. (b) In eukaryotic SECIS elements, conserved features (quartet, AA in the apical loop or bulge and an A preceding the quartet) are shown in blue. Bacterial elements are from deiodinase-like protein, AACY01143874; GPx, AACY01190440; and SelW-like protein, AACY01475618. Eukaryotic elements are from deiodinase, NM_000792, Homo sapiens; GPx, X68314, H. sapiens; SelW, AY221261, Danio rerio.