Selectivity of the yeast nuclear pore complex - probing transport in vivo

The Nuclear Pore Complex (NPC) is the main gateway for transport in and out of the nucleus. The main tasks are to separate transcription and translation and to allow for fast transport between cytoplasm and nucleus. The complex forms a barrier for the diffusion of proteins. In a systematic analysis using reporter proteins we studied the effect of size on the diffusion through the NPC of soluble and membrane proteins. The unfolded proteins in the center of the pore form a barrier, and specific proteins are essential to form this barrier. We compared the results with a computer model of the unfolded proteins in the NPC and this showed a clear correlation between the density in the center of the channel with the leakiness of the NPC. The approach with reporter proteins can also be applied to study the function of the NPC in ageing cells. By following yeast cells in a microfluidic chip the role and function of the NPC in ageing can be studied. The active transport of membrane proteins to the inner nuclear membrane also need to go via the NPC, but the route through the complex is still unclear. Some membrane proteins that localize in the nucleus have an unfolded linker domain that is essential for transport. The size and flexibility of this linker are essential properties for efficient transport.