Practice question

Eukaryotic and archaeal pre-tRNAs often carry intervening sequences in anticodon loop between positions 37 and 38. Unlike spliceosomal or self-splicing introns, tRNA intron excision requires protein enzymes: heterotetrameric tRNA splicing endonuclease TSEN complex makes two precise cuts excising intron, generating 5' and 3' halves with unusual cyclic phosphate termini. Subsequent healing by kinase, phosphodiesterase and ligase activity (RtcB or Trl1) rejoins exons using ATP. This enzyme-mediated pathway occurs in nucleus and distinguishes tRNA splicing from Group I self-splicing. This refined regulation supports accurate ribosomal assembly, quality control and translational fidelity under diverse physiological conditions and growth states.