Title: [36] Sequences and classification of group I and group II introns
Abstract: This chapter presents sequences and classification of group I and group II introns. The splicing of precursor RNAs (preRNAs) containing group I introns proceeds by a two-step transesterification mechanism, initiated by attack of the 3′-hydroxyl group of a free guanosine nucleotide on the 5′ splice site. Splicing of preRNAs containing group II introns is initiated by the attack on the 5′ splice site by the T-hydroxyl group of a particular adenosine residue near the 3′ end of the intron. A number of group II introns are capable of folding into a distinctive and complex secondary structure containing six helical segments, as well as a significant number of conserved nucleotides. The two known examples of self-splicing group II introns, intron 5 of the Saccharomyces cerevisiae mitochondrial cytochrome oxidase subunit I gene and intron of the yeast mitochondrial apocytochrome b gene are members of this more complex subgroup. Other chloroplast group II introns do not show the complex internal folding structure, but do have the characteristic group II consensus sequences at the splice sites, as well as the 14-bp major hairpin.
Publication Year: 1989
Publication Date: 1989-01-01
Language: en
Type: article
Indexed In: ['crossref', 'pubmed']
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Cited By Count: 6
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