Functions as a component of the nuclear pore complex (NPC). NPC components; collectively referred to as nucleoporins (NUPs); can play the role of both NPC structural components and of docking or interaction partners for transiently associated nuclear transport factors. Active directional transport is assured by both; a Phe-Gly (FG) repeat affinity gradient for these transport factors across the NPC and a transport cofactor concentration gradient across the nuclear envelope (GSP1 and GSP2 GTPases associated predominantly with GTP in the nucleus; with GDP in the cytoplasm). NUP53 may play an important role in cell cycle regulation by inhibiting PSE1 transport functions during mitosis and sequestration of MAD1-MAD2 in a cell cycle-dependent manner. It also seems to play an important role in de novo NPC assembly by associating with nuclear membranes and driving their proliferation. {ECO:0000269|PubMed:11352933; ECO:0000269|PubMed:12403813; ECO:0000269|PubMed:12473689; ECO:0000269|PubMed:12604785; ECO:0000269|PubMed:14697200; ECO:0000269|PubMed:9864357}.