Multifunctional protein that exhibits several independent functions at different levels of the cellular processes (PubMed:8188690, PubMed:1637812). 5'-3' exonuclease component of the nonsense-mediated mRNA decay (NMD) which is a highly conserved mRNA degradation pathway, an RNA surveillance system whose role is to identify and rid cells of mRNA with premature termination codons and thus prevents accumulation of potentially harmful truncated proteins (By similarity). Involved in the degradation of several hypomodified mature tRNA species and participates in the 5'-processing or the degradation of the snoRNA precursors and rRNA processing (By similarity). Strand exchange activity is enhanced by fatty acid synthase (stimulatory factor P190/210). Monomer. Belongs to the 5'-3' exonuclease family.