TRANSCRIPTION OF RAT MITOCHONDRIAL NADH-DEHYDROGENASE SUBUNITS PRESENCE OF ANTISENSE AND PRECURSOR RNA SPECIES

We have characterized the transcriptional pattern of the rat mitochond rial ND6-containing region in vivo. We have identified a stable polyad enylated RNA species complementary for the full length of the ND6 mRNA . The analysis of the ND5 region has revealed the presence of an antis ense RNA only at its 3' end. The presence of these stable antisense sp ecies complementary to structural genes is intriguing and suggests a p ossible regulatory function. The quantitative analyses have demonstrat ed that the H transcripts, both codogenic and non-codogenic, are more stable than the L transcripts. We have defined the 5' end of the ND6 m RNA at the level of the ATG downstream of the tRNA(Glu). The mapping o f the ND1 5' end has demonstrated that GTG is the first codon of the m RNA. Our findings suggest that the post-transcriptional mechanisms inv olved in the expression of the mt genome are much more numerous and co mplex than those already described in the literature.