Читать книгу Algorithms in Bioinformatics - Paul A. Gagniuc - Страница 20

Introns are regions that interrupt the coding region of functional RNA or protein-coding genes. There are four known classes of introns: Group I introns, Group II Introns, nuclear pre-mRNA introns (Spliceosomal introns), and transfer RNA (tRNA) introns. Group I introns are self-splicing introns and are found in some ribosomal RNA (rRNA) genes [43]. Group II introns are mobile ribozymes that self-splice from precursor RNAs (pre-RNAs) and are found in bacterial genomes and organellar genomes, suggesting that catalytic RNAs, as informational structures, predate the origin of eukaryotes and perhaps the origin of cellular life [44, 45]. Nuclear pre-mRNA introns are found in protein-coding genes and require a ribonucleoprotein complex (spliceosomes) for splicing. The tRNA introns are found in various tRNA genes in all the three kingdoms of life, and require certain enzymes for splicing [46].