Abstract
Transfer RNA biosynthesis in eucaryotic cells involves processing of a primary transcript to mature tRNA by cleavage of sequences from the 5' and 3' ends. Following processing within the nucleus, mature tRNA is transported into the cytoplasm. We have recently demonstrated the existence of a tRNA transport system in Xenopus oocytes (Proc. Natl. Acad. Soc., 80, 6436-6440, (1983)). Studies of a cloned human variant tRNA (met)i gene, which contains a base substitution in the loop IV region, suggested that nucleolytic processing and transport might be functionally linked. The primary transcript of the variant gene is processed slowly and the mature variant tRNA species, although accurately processed, accumulates in the nucleus and is not transported. In order to define the nucleotides in a normal human tRNA (met)i gene involved in processing and transport, we have generated, by in vitro methods, mutants which contain one or a few C→T transitions in the tRNA coding sequence. The effect of these altered nucleotides on processing has been assessed in vivo by micro-injection of cloned mutant tRNA genes into the oocyte nucleus and in vitro by reaction of the mutant primary transcripts with the purified processing nucleases. The transport properties of the mutant tRNA genes have been analyzed following micro-dissection of nuclear and cytoplasmic components from oocytes injected with mutant tRNAs in the nucleus. Nucleotide changes independently affecting transport or processing have been observed showing the processes are not functionally linked.
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Tobian, J., Castano, J. & Zasloff, M. 864 EXPLORING THE MECHANISM OF NUCLEAR RNA TRANSPORT WITH MUTANT HUMAN tRNA GENES. Pediatr Res 19, 254 (1985). https://doi.org/10.1203/00006450-198504000-00894
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DOI: https://doi.org/10.1203/00006450-198504000-00894