Accurate and efficient transcription of human c-myc genes injected into Xenopus laevis oocytes.

We investigated the expression of the cloned human c-myc gene in Xenopus laevis oocytes microinjected with different recombinants. We found that microinjected plasmid DNA carrying an intact human c-myc gene directs efficient and faithful transcription from its own two promoters in X. laevis oocytes. This active transcription was unaffected by the presence of previously identified enhancing elements such as simian virus 72-base pair repeats or mouse immunoglobulin heavy-chain gene enhancer sequences in the construct in cis. This suggests that all necessary DNA sequences for accurate and faithful transcription recognized by the transcription machinery of the frog oocyte are self-contained. In addition, we have found that human c-myc transcripts synthesized in oocytes are properly polyadenylated at either one of two sites and also that the transcripts are spliced correctly but with low efficiency.