Regulation of the human c-myc gene: 5' noncoding sequences do not affect translation.
The influence of untranslated 5' sequences on c-myc expression was compared by measuring the translational efficiencies of mRNAs which contain leaders derived from exon 1 or intron 1 of the human c-myc gene. Expression plasmids were constructed and introduced into COS cells, and the levels of c-myc mRNA and protein were examined. Our results show that mRNAs transcribed from constructs containing exon 1 or intron 1, which have different folding potential, are translated with approximately equal efficiencies. This suggests that the translation of c-myc mRNA is not controlled by secondary structure alone. In addition, we observed that transcripts in which exon 1 was deleted are not translated more efficiently, but are present at a higher steady-state level. Thus, this example provides evidence for possible control at the transcriptional level. Finally, since the c-myc product was produced in each of our test systems, the results suggest that this protein does not regulate its own transcription or translation via a specific interaction with c-myc exon 1 alone.
D000818:Animals; D001483:Base Sequence; D002460:Cell Line; D002522:Chlorocebus aethiops; D004262:DNA Restriction Enzymes; D005796:Genes; D005809:Genes, Regulator; D006801:Humans; D007328:Insulin / Q000235:genetics; D007668:Kidney; D009857:Oncogenes; D010957:Plasmids; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000235:genetics*
D007328:Insulin; D012333:RNA, Messenger; D004262:DNA Restriction Enzymes