FIGURE 3.

Two novel A-to-I editing sites were predicted and experimentally verified in squid sytI. (A) Comparison of amino acid sequences from various sytI orthologs. Abbreviations: Hsa: H. sapiens (AAA60609; BAC04354); Xla: X. laevis (CX838804, CX794956); Dre: D. rerio (NP_001018382, XM_683000.2; XM_691185.2); Lpe: L. pealei (CAA51079.1); Dme: D. melanogaster (AAF51205); Aga: A. gambiae (XP_317535); Bmo: B. mori (Scaffold005935); Tca: T. castaneum (XP_969399); Mse: Manduca sexta (AAK01129); Ame: A. mellifera (XP_392154); Aca: A. californica (AAQ91785; P41823); Lst: L. stagnalis (AAO83847); Dom: Discopyge ommata (AAA49228.1); Pdu: Platynereis dumerilii (ABR68850.1); Dja: Dugesia japonica (BAA85622); Spu: S. purpuratus (AAB67801.3); Hro: H. robusta (BAB18864); Cel: Caenorhabditis elegent (NP_001022129). RNA editing of the sytI in insects has been described previously (Reenan 2005). Amino acid residues showing complete conservation are shaded in red. Residues recoded by RNA editing are shaded in green, and genomic substitutions with edited residues at these positions are shaded in turquoise. Two candidate residues (shaded in dark blue) altered by RNA editing are predicted in squid. (B) Two editing sites in squid (Loligo chinensis) sytI are experimentally verified and compared to fruit fly (D. melanogaster) and silkworm (B. mori). RNA editing results in substitution of Ile to Val at the V334 ortholog site in the fruit fly, and in substitution of Thr to Ala at A350 ortholog site in the silkworm. Reverse transcriptase reactions were performed with oligo(dT)₁₅ on total RNA from squid. The RT-PCR and PCR products were purified for direct sequencing. The editing sites (arrow) showed an A/G mixed signal, while the DNA sequence exhibited only adenosine signals.