Figure 1.

Cleavage of pre-tRNA by the TSEN complex, the current model of tRNA cleavage. The human TSEN complex is composed of four subunits including two endonucleases (TSEN2 and TSEN34) and two structural components (TSEN15 and TSEN54). Current models for tRNA splicing in metazoans suggest that the TSEN complex requires assistance from CLP1 to catalyze tRNA intron removal (light gray). Following cleavage by the TSEN complex, the 5′ exon and intron contain a 2′,3′ - cyclic phosphate and the 3′ exon and intron contain a 5′-OH.