The major transcripts of the kinetoplast DNA of Trypanosoma brucei are very small ribosomal RNAs.

The nucleotide sequence has been determined of a 2.2 kb segment of kinetoplast DNA, which encodes the major mitochondrial transcripts (12S and 9S) of Trypanosoma brucei. The sequence shows that the 12S RNA is a large subunit rRNA, although sufficiently unusual for resistance to chloramphenicol to be predicted. The 9S RNA has little homology with other rRNAs, but a possible secondary structure is not unlike that of the 2.5-fold larger E. coli 16S rRNA. We conclude that the 12S RNA (about 1230 nucleotides) and the 9S RNA (about 640 nucleotides) are the smallest homologues of the E. coli 23S and 16S rRNAs yet observed.