Protein with different functions depending on its subcellular location: involved in miRNA processing in the nucleus and acts as a tRNA pseudouridylate synthase in the cytoplasm. In the cytoplasm, acts as a pseudouridylate synthase by catalyzing synthesis of pseudouridine(54) and pseudouridine(55) from uracil-54 and uracil-55, respectively, in the psi GC loop of a subset of tRNAs. tRNA pseudouridylate synthase activity is enhanced by the presence of 1-methyladenosine at position 53-61 of tRNAs. Does not show tRNA pseudouridylate synthase activity in the nucleus. In the nucleus, promotes primary microRNAs (pri-miRNAs) processing independently of its RNA pseudouridylate synthase activity. Binds pri-miRNAs. Modulator of TRAIL/TNFSF10-induced cell death via activation of procaspase-8 and BID cleavage. Required for the progression of the apoptotic signal through intrinsic mitochondrial cell death. uridine(55) in tRNA = pseudouridine(55) in tRNA uridine(54) in tRNA = pseudouridine(54) in tRNA Interacts with components of the microprocessor complex DROSHA and DGCR8. Localizes mainly in the nucleus. tRNA pseudouridylate synthase activity is restricted to the cytoplasm. Translocates from nucleus to mitochondria during TRAIL-induced apoptosis. Proteolytically cleaved during TRAIL-induced cell death. Cleaved, in vitro, either by caspase-3 (CASP3) or caspase-8 (CASP8). Belongs to the pseudouridine synthase Pus10 family.