The Nuclear Pore Complex (NPC) is a large protein structure that spans the nuclear envelope, which separates the nucleus from the cytoplasm in eukaryotic cells. It functions as a gateway, allowing the transport of molecules such as proteins and RNA between the nucleus and the cytoplasm. The NPC is composed of multiple proteins called nucleoporins, which form a complex structure that regulates the passage of substances. The NPC is essential for maintaining cellular function and gene expression. It ensures that necessary molecules can enter the nucleus for processes like DNA replication and transcription, while also allowing the export of completed mRNA and ribosomal subunits. This selective transport is crucial for the overall health and operation of the cell.