||"Eukaryotic chromosomes are confined to the nucleus, which is separated
from the rest of the cell by two concentric membranes known as the nuclear envelope (NE). The NE is punctuated
by holes known as nuclear pore complexes (NPCs), which provide the main pathway for transport of cellular
material across the nuclear-
cytoplasmic boundary. The single NPC is a complicated octameric structure containing
more than 100 proteins called nucleoporins. NPCs function as transport machineries for inorganic ions and
macromolecules. The most prominent feature of an individual NPC is a large central channel, ~7 nm in width and
50 nm in length. NPCs exhibit high morphological and functional plasticity, adjusting shape to function."