tRNA-splicing endonuclease subunit Sen34 is an enzyme that in humans is encoded by the TSEN34 gene.

This gene encodes a catalytic subunit of the tRNA splicing endonuclease, which catalyzes the removal of introns from precursor tRNAs. The endonuclease complex is also associated with a pre-mRNA 3-prime end processing factor. A mutation in this gene results in the neurological disorder pontocerebellar hypoplasia type 2. Multiple alternatively spliced variants, encoding the same protein, have been identified.[provided by RefSeq, Oct 2009].
Function: Constitutes one of the two catalytic subunit of the tRNA-splicing endonuclease complex, a complex responsible for identification and cleavage of the splice sites in pre-tRNA. It cleaves pre-tRNA at the 5'- and 3'-splice sites to release the intron. The products are an intron and two tRNA half-molecules bearing 2',3'-cyclic phosphate and 5'-OH termini. There are no conserved sequences at the splice sites, but the intron is invariably located at the same site in the gene, placing the splice sites an invariant distance from the constant structural features of the tRNA body. It  probably carries the active site for 3'-splice site cleavage. The tRNA splicing endonuclease is also involved in mRNA processing via its association with pre-mRNA 3'-end processing factors, establishing a link between pre-tRNA splicing and pre-mRNA 3'-end formation, suggesting that the endonuclease subunits function in multiple RNA-processing events.