The nuclear pore complex (NPC) is a large channel that spans the two lipid 
bilayers of the nuclear envelope and mediates transport events between the 
cytoplasm and the nucleus. Only a few NPC components are transmembrane proteins, 
and the role of these proteins in NPC function and assembly remains poorly 
understood. We investigate the function of the three integral membrane 
nucleoporins, which are Ndc1p, Pom152p, and Pom34p, in NPC assembly and 
transport in Saccharomyces cerevisiae. We find that Ndc1p is important for the 
correct localization of nuclear transport cargoes and of components of the NPC. 
However, the role of Ndc1p in NPC assembly is partially redundant with Pom152p, 
as cells lacking both of these proteins show enhanced NPC disruption. Electron 
microscopy studies reveal that the absence of Ndc1p and Pom152p results in 
aberrant pores that have enlarged diameters and lack proteinaceous material, 
leading to an increased diffusion between the cytoplasm and the nucleus.