NXF1NXT1

NXF1NXT1 refers to the heterodimer formed by Nuclear Export Factor 1 (NXF1) and Nuclear Transport Factor 1 (NXT1). In vertebrates and many other eukaryotes, this complex acts as the principal mRNA export receptor, transporting mature messenger RNA from the nucleus to the cytoplasm. NXF1 is often stabilized and regulated by its partner NXT1, also known as p15 in some species.

The NXF1NXT1 heterodimer binds to export-competent mRNPs (messenger ribonucleoproteins) through interactions with adapter proteins such as Aly/REF and the THO complex. Once assembled on processed mRNA, the complex engages FG-repeat nucleoporins in the nuclear pore complex (NPC) and mediates translocation of the mRNP across the nuclear envelope. The export process is largely Ran-independent and relies on the coordinated remodeling of the mRNP and its contacts with the NPC.

Function and significance: The NXF1NXT1 complex is essential for gene expression, ensuring that mature mRNA reaches the cytoplasm for translation. Its activity is tightly regulated during RNA processing and export, and disruption of the complex leads to nuclear retention of mRNA and widespread defects in protein synthesis. The mechanism is highly conserved from yeast to humans, reflecting its fundamental role in cellular biology.

Clinical and research relevance: Altered NXF1/NXT1 function has been linked to conditions involving impaired mRNA export and cellular stress responses. Some viruses exploit the complex to promote export of viral RNAs. As a central node in post-transcriptional regulation, the complex remains a focus of studies on gene expression and potential therapeutic targets.