SEN15, also known as TSEN15 (tRNA-splicing endonuclease subunit Sen15) or C1orf19, is a nuclear protein that plays a role in tRNA splicing. Widely expressed with highest expression in testis and uterus, SEN15 is a non-catalytic subunit of the multi-protein tRNA-splicing endonuclease complex. The endonuclease complex is responsible for identifying and cleaving pre-tRNA at both 5’ and 3’ splice sites, thereby releasing introns and free tRNA molecules with 2',3' cyclic phosphates and 5'-OH termini. In addition to its role in pre-tRNA splicing, the endonuclease complex participates in mRNA processing and, via its association with pre-mRNA processing factors, is thought to link pre-tRNA and pre-mRNA splicing events. As a subunit of the complex, SEN15 participates in protein expression and, ultimately, cell growth and division.