RNA-binding protein involved in modulation of mRNA transcription by Polymerase II. Component of the tRNA-splicing ligase complex and is required for tRNA ligation. May be required for RNA transport. Homodimer. Interacts with FAM98A (via N- and C-terminus). Interacts with NIN; which may prevent phosphorylation of NIN. Interacts with POLR2A. Component of a tRNA-splicing ligase complex. May localize at the centrosome during mitosis. Shuttles between the cytosol and the nucleus: enters into the nucleus in case of active transcription while it accumulates in cytosol when transcription level is low. Belongs to the RTRAF family.