Nuclear export factor (NXF) proteins belong to an evolutionarily conserved family of proteins which are characterized by a leucine-rich-repeat domain(LRR) followed by a region known as the Nuclear Transport Factor 2 (NTF2)-like domain. The NXF family includes TAP1 (NXF1) and NXF2-5. TAP1 mediates the export of constitutive transport element (CTE)-containing simian type D retroviral RNAs through direct binding to the CTE. NXF2 binds RNA and localizes to the nuclear envelope, where it exhibits RNA export activity. NXF3 does not bind RNA nor localize to the nuclear rim, and NXF3 does not exhibit RNA export activity. NXF5 binds RNA and localizes in the form of granules in the cell body and neurites of mature hippocampal neurons. TAP1, NXF2 and NXF5 form heterodimers with RNA nuclear export-associated protein p15 (NXT). The human NXF gene cluster maps to Xcen-NXF5-NXF2-NXF4-NXF3-Xqter.