RNA-binding RNA annealing protein. May have a role in pre-mRNA metabolism. Component the TREX complex, which operates in coupling transcription elongation to mRNA export. Component of the transcription/export (TREX) complex, which is at least is formed of SUB2, TEX1 and YRA1 and the THO complex composed of HPR1, MFT1, THO2 and THP1. Interacts with RDS3 and YRA2.