The sequence of a gene in Drosophila melanogaster that encodes a histone H2A polypeptide is as follows:

aagtagtcgaaaccgaattccgtagaaacaactcgcacgctccggtttcgtgttgcaacaaaataggcattcccatcgcggcagttagaatcaccgagtgcccagagtcacgttcgtaagcaggcgcagtttacaggcagcag
aaaaatcgattgaacagaaatggctggcggtaaagcaggcaaggattcgggcaaggccaaggcgaaggcggtatcgcgttccgcgcgcgcgggtcttcagttccccgtgggtcgcatccatcgtcatctcaag
agccgcactacgtcacatggacgcgtcggagccactgcagccgtgtactccgctgccatattggaatacctgaccgccgaggtcctggagttggcaggcaacgcatcgaaggacttgaaagtgaaacgtatcactcc
tcgccacttacagctcgccattcgcggagacgaggagctggacagcctgatcaaggcaaccatcgctggtggcggtgtcattccgcacatacacaagtcgctgatcggcaaaaaggaggaaacggtgcaggatccgc
agcggaagggcaacgtcattctgtcgcaggcctactaagccagtcggcaatcggacgccttcgaaacatgcaacactaatgtttaattcagatttcagcagagacaagctaaaacaccgacgagttgtaatcatttctgtgcg
ccagcatatatttcttatatacaacgtaatacataattatgtaattctagcatctccccaacactcacatacatacaaacaaaaaatacaaacacacaaaacgtatttacccgcacgcatccttggcgaggttgagtatgaaacaaa
aacaaaacttaatttagagcaaagtaattacacgaataaatttaataaaaaaaactataataaaaacgcc.

Let’s use the translation software available on the Internet at http://www.expasy.org/tools/dna.html to translate this gene in all six possible reading frames and see which reading frame specifies histone H2A. Just type or paste the DNA sequence in the “ExPASy Translate” tool box and click TRANSLATE SEQUENCE. The results will show the products of translation in all six reading frames with Met’s and Stop’s boldfaced to highlight potential open-reading frames. Which reading frame specifies histone H2A?