To identify human orthologs of mouse OPRM1 exons, we confirmed the synteny within the full-length sequences of the human and mouse OPRM1 genes and analyzed patterns of similarity in inter-species comparisons using detailed pairwise alignments (36). We used mRNA sequences of known alternatively spliced isoforms of mouse OPRM1 and GenBank annotations to refine locations of the initial and terminal exons and to identify unknown human orthologous exons (37). In addition, we performed an extensive search for regulatory sites, structural elements and splicing signals (38–42) to reveal putative sites of initiation and termination of transcription and to refine exon/intron boundaries.
