Porikompleksit

Porikompleksit, sometimes referred to as pore complexes, are intricate protein structures that form channels through the nuclear envelope of eukaryotic cells. These complexes are essential for regulating the transport of molecules between the nucleus and the cytoplasm. They are not simply passive pores but dynamic gateways that actively control what enters and exits the nucleus.

The nuclear envelope itself is a double membrane that encloses the cell's genetic material. Within this envelope, the porikompleksit are embedded, creating a barrier that separates the nuclear contents from the cytoplasm. The size and composition of these complexes allow for selective passage. Small molecules, such as ions and metabolites, can diffuse relatively freely through the porikompleksit.

However, larger molecules, like proteins and RNA, require specific signals for transport. These signals, often in the form of nuclear localization signals (NLS) or nuclear export signals (NES) on the molecules themselves, are recognized by transport receptor proteins. These receptors then bind to the porikompleksit and facilitate the translocation of their cargo across the nuclear envelope. This regulated transport is crucial for gene expression, DNA replication, and other vital nuclear functions. The precise mechanisms by which porikompleksit achieve this selectivity are still an active area of research.