What is the function of the nuclear pores?

The function of nuclear pores is to regulate the exchange of materials between the nucleus and the cytoplasm.

Nuclear pores are complex structures that punctuate the nuclear envelope, which is the double membrane surrounding the nucleus in a eukaryotic cell. These pores serve as gatekeepers, controlling the movement of molecules in and out of the nucleus. They are essential for the proper functioning of the cell as they facilitate the transport of a variety of substances, including proteins, RNA, and ribosomal subunits.

The nuclear pore complex (NPC) is a large protein assembly composed of around 30 different proteins known as nucleoporins. These nucleoporins form a channel through which small water-soluble molecules can freely diffuse, while larger molecules require active transport. This active transport is highly selective and is regulated by specific signal sequences on the molecules to be transported.

Proteins that need to enter the nucleus, for instance, carry a nuclear localisation signal (NLS). This signal is recognised by importin, a transport protein, which binds to the protein and guides it through the nuclear pore. Similarly, RNA molecules and ribosomal subunits that need to exit the nucleus carry a nuclear export signal (NES), which is recognised by exportin.

The nuclear pores also play a crucial role in maintaining the integrity of the genome. They prevent the DNA from coming into direct contact with the cytoplasm, thereby protecting it from potential damage. Furthermore, they are involved in the regulation of gene expression, as the transport of RNA and proteins can influence which genes are expressed at any given time.

In summary, nuclear pores are vital for the functioning of eukaryotic cells. They regulate the transport of molecules between the nucleus and the cytoplasm, contribute to genome integrity, and play a role in gene expression.