The central compartment of the nuclear pore complex (NPC), allowing the nuclear-cytoplasmic transport of molecules, consists of transmembrane proteins which anchor the pore in the nuclear envelope. Morphological and morphometric analyses of nuclear pore organization in Saccharomyces cerevisiae with mutations in the POM152 and POM34 genes have been performed. The absence of Pom152 or Pom34 initiates the disruption of the nuclear pore complex assembly. As a result, their quantity in the nuclear envelope decreases. Electron-microscopic examination shows that the inhibition of POM152 expression is also accompanied by an increase in the NPC inner diameter not observed in mutant cells with Pom34 depletion. Interactions of the transmembrane proteins with other nucleoporins and their role in pore reconstruction during cell division are discussed.