Many trypanosome messenger RNAs share a common 5' terminal sequence.
The mRNAs for different variant surface antigens of Trypanosoma brucei start with the same 35 nucleotides. This sequence is encoded by a separate mini-exon, located in a 1.35-kb repetitive element. We have reported that trypanosomes contain many transcripts that hybridize to mini-exon probes, even if they do not make the surface antigens. We show here that these transcripts have the mini-exon sequence at their 5' end; they do not contain other sequences from the mini-exon repeat element and are polyadenylated. We have cloned DNA complementary to trypanosome mRNAs and randomly selected 17 clones containing mini-exon sequences. Thirteen of these are derived from different genes that do not code for surface antigens. We conclude that the mini-exon sequence is a common element at the 5' end of many trypanosome mRNAs. As the 200 genes for mini-exons are highly clustered, linkage of the mini-exon sequence to the remainder of most mRNAs may require discontinuous transcription.
D000595:Amino Acid Sequence; D000818:Animals; D001482:Base Composition; D001483:Base Sequence; D003001:Cloning, Molecular; D004247:DNA / Q000378:metabolism; D005796:Genes; D006023:Glycoproteins / Q000235:genetics*; D009693:Nucleic Acid Hybridization; D012333:RNA, Messenger / Q000235:genetics*; D012091:Repetitive Sequences, Nucleic Acid; D014158:Transcription, Genetic; D014346:Trypanosoma brucei brucei / Q000276:immunology*; D014643:Variant Surface Glycoproteins, Trypanosoma
D006023:Glycoproteins; D012333:RNA, Messenger; D014643:Variant Surface Glycoproteins, Trypanosoma; D004247:DNA