tRNA introns

BACK to 'Hemiascomycetous Yeast Spliceosomal Introns'

1. Phylogenetic distribution: Ubiquitous
   

   Eukarya

   Archaea

   Eubacteria




2. Location
   

   In nuclear tRNA genes (single intron)

   Small insertions invariably located in the anti-codon loop between the first two bases 3' of the anticodon in Eukaryotes, and in slightly locations in Archaea.




3. Size
   

   14-60 nucleotides




4. Sequence
   

   no splice site consensus

   no consensus sequences, recognition by enzymes is indirect

   complementary to anti-codon, allows folding into alternate conformation







5. Splicing mechanism: Enzymatic cascade (Eukarya and Archaea)
   

   Unusual splicing mechanism that relies upon 3-D structure rather than sequence.

   Catalysed by a cascade of specialised enzymes.

   Mechanism is slightly different between yeasts and vertebrates.




6. Requirement for an external source of energy (ATP).
   
   
7. ORF-less and Non-mobile.