U12 intron positions are more strongly conserved between animals and plants than U2 intron positions.
We report that the positions of minor, U12 introns are conserved in orthologous genes from human and Arabidopsis to an even greater extent than the positions of the major, U2 introns. The U12 introns, especially, conserved ones are concentrated in 5'-portions of plant and animal genes, where the U12 to U2 conversions occurs preferentially in the 3'-portions of genes. These results are compatible with the hypothesis that the high level of conservation of U12 intron positions and their persistence in genomes despite the unidirectional U12 to U2 conversion are explained by the role of the slowly excised U12 introns in down-regulation of gene expression.
Basu
Malay Kumar
MK
National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD, USA. mbasu@ncbi.nlm.nih.gov
Makalowski
Wojciech
W
Rogozin
Igor B
IB
Koonin
Eugene V
EV
D000818:Animals; D017360:Arabidopsis / Q000235:genetics*; D001483:Base Sequence; D017124:Conserved Sequence / Q000235:genetics*; D006801:Humans; D007438:Introns / Q000235:genetics*; D012342:RNA, Small Nuclear / Q000235:genetics*; D017422:Sequence Analysis, DNA / Q000706:statistics & numerical data
D012342:RNA, Small Nuclear; C096986:U12 small nuclear RNA; C405484:U2 small nuclear RNA