BIOL 200 Lecture 24: Nuclear pore complexes (NPC)
Document Summary
Molecules up to 60kda can freely diffuse thru npc. Bigger molecules & multimolecular complexes (rnps) must be actively transported. Lumen: space b/w the two membranes (nuclear envelope) of the npc. Basically, you have 2 membranes, sealed off, enclosing a space in b/w that contains lumen, which provides structure and rigidity for the nuclear pore. Cytoplasmic filaments: proteins that project out onto the cytoplasmic side. Site of recruitment of a number of regulatory components that are involved in import & export of proteins into nucleus or into cytoplasm. Transporters also have hydrophobic repeats; these repeats interact with those on the mesh (fg nucleoporins), allowing them to go thru the npc. These nuclear proteins contain a nls (nuclear localization signal), which is essential & sufficient for nuclear localization. 2 proteins required for nuclear import: ran; nuclear transport receptors. Exists in 2 conformations: one when bound to. Active (on) when bound to gtp; inactive (off) when bound to gdp.
