FIGURE 1.
Two overlapping open reading frames coexist in the A2AR gene. A, the major mRNA of the Adora2a gene (GenBankTM accession number BC081727) that contains 5′-UTR (−243/−1) and coding regions for both A2AR (solid box, +1 reading frame) and uORF5 (dashed line box, +2 reading frame). The translation start site of A2AR is located at +1 (AUG), and the translation start site of uORF5 is located at −65 (uAUG5). The asterisks mark the stop codons of A2AR (+1233) and uORF5 (+340). B, translation start sites are underlined. The asterisk marks the stop codon of uORF5. The overlapping region of uORF5 and A2AR is 340 nucleotides. The entire aa sequence of uORF5 and the first 134 aa of A2AR are shown below the DNA sequence. C, alignment of the predicted aa sequences of the human (CA307692), chimpanzee (XM_003953847), rat (BC081727), and mouse (AC137067) uORF5 proteins. Amino acid identity was as follows: rat versus human, 75%; rat versus chimpanzee, 75%; rat versus mouse, 84%.