UAP56 Interacting Factor (UIF)

The canonical adaptor REF/ALY/Yra1 is recruited to mRNA via UAP56 and subsequently delivers the mRNA to NXF1. Knockdown of UAP56 and NXF1 in higher eukaryotes efficiently blocks mRNA export, whereas knockdown of REF only causes a modest reduction, suggesting the existence of additional adaptors.UIF, which functions as an export adaptor, binding NXF1 and delivering mRNA to the nuclear pore. REF and UIF are simultaneously found on the same mRNA molecules, and both proteins are required for efficient export of mRNA. The histone chaperone FACT specifically binds UIF, but not REF, via the SSRP1 subunit, and this interaction is required for recruitment of UIF to mRNA. Together the results indicate that REF and UIF represent key human adaptors for the export of cellular mRNAs via the UAP56-NXF1 pathway.