Conserved sequences in both coding and 5′ flanking regions of mammalian opal suppressor tRNA genes

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Abstract
The rabbit genome encodes an opal supressor tRNA gene. The coding region is strictly conserved between the rabbit gene and the corresponding gene in the human genome. The rabbit opal supressor gene contains the consensus sequence in the 3′ internal control region but like the human ad chicken genes, the rabbit 5′ internal control region contains two additional nucleotides. The 5′ flanking sequences of the rabbit and the human opal suppressor genes contain extensive regions of homology. A subset of these homologies is also present 5′ to the chicken opal suppressor gene. Both the rabbit ad the human genomes also encode a pseudogene. That of the rabbit lacks the 3′ half of the codin region. Neither pseudogene has homologous regions to the 5′ flanking regions of the genes. The presence of 5′ homologies flaking only the transcribed genes and not the pseudogenes suggests that these regions may be regulatory control elements specifically involved in the expression of the eukaryotic opal suppressor gene. Moreover the strict conservation of coding sequences indicates functional importance for the opal supressor tRNA genes.