Stimulator of protein export for NES-containing proteins (PubMed:10567585). Also plays a role in the nuclear export of U1 snRNA, tRNA, and mRNA (PubMed:10848583). The NXF1-NXT1 heterodimer is involved in the export of HSP70 mRNA in conjunction with ALYREF/THOC4 and THOC5 (PubMed:19165146, PubMed:11259602). Heterodimer with NXF1 (PubMed:11583626). Forms a complex with RANGAP1, RANBP2/NUP358 and NXF1 (PubMed:14729961). Interacts (via NTF2 domain) with NXF1 (PubMed:11583626). Stabilizes the NTF2 domain of NXF1 by heterodimerization (PubMed:11583626). The formation of NXF1-NXT1 heterodimers is required for the NXF1-mediated nuclear mRNA export (PubMed:11583626). Preferentially binds Ran-GTP (PubMed:10567585). Associates with NXF2, NXF3 and NXF5. Does not bind nucleoporins (NPC) directly, its association to NPC is mediated by NXF1 (PubMed:11583626). Shuttles between the nucleus and the cytoplasm.