Logistics on smallest possible space: Transport processes between cell nucleus and cytoplasm

The cell nucleus is enclosed by the nuclear envelope, lacks protein synthesis and therefore imports each and every protein from the cytosol. Conversely, the nucleus supplies the cytoplasm with nuclear products, such as ribosomes, tRNAs and mRNAs. The permeability barrier of nuclear pore complexes controls all this exchange. This permeability barrier is an "intelligent" hydrogel with truly remarkable properties. It excludes inert macromolecules, but permits an up to 20 000-fold faster entry of cargoes, when these are bound to appropriate nuclear transport receptors.