Group I introns: Moving in new directions.
Group I introns are genetic elements interrupting functional genes. They are removed from precursors at the RNA level and most catalyze their own splicing. The catalytic part of these constitutes one of the major classes of catalytic RNAs, the group I ribozymes. However, group I introns have a lot more to offer than their own elimination by splicing. Intron RNA can circularize in at least three different ways and introns are mobile both at the DNA and RNA level. Some group I introns have a very complex organization incorporating functional genes and other sequence elements and have established deep relationships with their host genomes. Finally, group I introns can develop into new ribozymes with new biological functions.
Nielsen
Henrik
H
Department of Cellular and Molecular Medicine, The Panum Institute, University of Copenhagen, Copenhagen, Denmark. Denmark. hamra@sund.ku.dk
Johansen
Steinar D
SD
D000818:Animals; D019143:Evolution, Molecular; D006801:Humans; D007438:Introns / Q000235:genetics*; D008954:Models, Biological; D009690:Nucleic Acid Conformation; D016337:RNA, Catalytic / Q000378:metabolism
C116167:GIR1 ribozyme; D016337:RNA, Catalytic