Plant Viral Leader Sequences

In order to optimize expression of proteins in transgenic plants, plant viral untranslated leader sequences are often used (Dowson et al., 1993). Plant viral leaders such as the TMV omega leader sequence can result in an enhancement of expression as great as tenfold. Mitsuhara et al. (1996) compared mRNA and protein levels and determined that mRNA containing the TMV leader sequence was translated more efficiently. This 5 untranslated sequence of TMV is routinely used for high transgene expression (Koziel et al., 1996). 

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Alterations to the proteins and pre-proteins expressed by cultured plant cells have been used to facilitate product recovery. A leader sequence is required for foreign protein secretion from plant cells into the apoplast and then into the culture medium. As indicated in Table 2.1, plant, mammalian and viral sequences have been employed to achieve the entry of transgenic proteins into the bulk-flow pathway in plant cultures. 

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