Part of the nuclear pore complex (PubMed:14638854). Serves as a docking site in the receptor-mediated import of substrates across the nuclear pore complex including emb, RanGAP and phosphorylated Mad (PubMed:17682050, PubMed:20547758, PubMed:17032737). Protects mbo/Nup88 from proteasomal degradation at the nuclear pore (PubMed:17032737). Together with mbo/Nup88, sequesters emb in the cytoplasm and thereby attenuates nuclear export signal (NES)-mediated nuclear export (PubMed:17032737). Together with mbo/Nup88, required for the nuclear import of the Rel family transcription factors dorsal (dl) and Dorsal-related immunity factor (Dif) and the activation of an immune response (PubMed:17032737). Component of the nuclear pore complex (PubMed:14638854). Interacts with mbo/Nup88 and (via C-terminus) with emb to attenuate emb-mediated protein export (PubMed:14638854, PubMed:17032737). Localization to the nucleus membrane depends on mbo/Nup88. Contains FG repeats. FG repeats are interaction sites for karyopherins (importins, exportins) and form probably an affinity gradient, guiding the transport proteins unidirectionally with their cargo through the NPC. FG repeat regions are highly flexible and lack ordered secondary structure. The overall conservation of FG repeats regarding exact sequence, spacing, and repeat unit length is limited. FG-rich region is required for emb localization to the nuclear pore complex.