Possible functionality of start and stop codons present at specific and conserved positions in animal mitochondrial genes specifying tRNA
Eric Faure, Roxane-Marie Barthélémy
Several metazoan mitochondrial-trn genes (specifying tRNA) exhibit nucleotide triplets at specific and conserved positions corresponding to stop codons (TAG/TAA) and/or start codons (ATG/ATA). The products of these genes, which bear one or two types of these codons are called ss-tRNAs (for stop/start). In this article, several examples of ss-trn genes bearing start or stop codons in metazoans (protostomes and deuterostomes) strongly suggest that these codons are functional. Moreover, the ss-trn genes found in apicoplast genomes likely have a mitochondrial origin, but the TAR and ATR triplets (R for purines) found in their sequences seem to play only a structural role. Future investigations should attempt to clarify the mechanisms of the transcription and maturation of ss-trn genes with their overlapping protein genes and the possible regulatory roles of stop and start codons found in trn sequences.
Eric Faure, Roxane-Marie Barthélémy. Possible functionality of start and stop codons present at specific and conserved positions in animal mitochondrial genes specifying tRNA. International Journal of Zoology Studies, Volume 4, Issue 3, 2019, Pages 23-29