The origin of the intervening sequences (introns), which are removed during RNA maturation, is currently unknown. They are found in most genes encoding messenger RNAs, but are lacking in almost all small nuclear (sn)RNAs. One exceptional snRNA (U6) is part of the spliceosomal machinery that is involved in messenger RNA maturation. It has been suggested that its intron arose as a result of incorrect splicing of a messenger RNA precursor. This study revealed the presence of an intron, with the characteristic features of nuclear introns from precursors to messenger RNA, in the two genes coding for Saccharomyces cerevisiae U3 snRNA. The branch point was GACTAAC instead of the TACTAAC sequence found in all yeast introns examined so far. As U3 is a nucleolar snRNA required for maturation of ribosomal RNA, its intron could not have been acquired from aberrant messenger RNA processing in a spliceosome.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|