NUCLEOCYTOPLASMIC TRANSPORT
Transport fig 1
All molecules larger than ~30kDa (or ~8nm) must display a signal to a transport receptor prior to moving through the NPC. Transport receptors bind this signal in preparation for transport. In this schematic, a transport receptor (orange arc) binds a cargo molecule (yellow circle). This receptor-cargo complex enters the NPC and moves through. As the complex moves through the pore, the receptor engages in multiple low-affinity interactions with FG-Nups (see below). Once the complex reaches the far side of the pore, its disassembly is catalyzed by the binding of RanGTP (blue hexagon). The cargo has now been delivered, and the receptor is ready for recycling back to the cytoplasm.


The Role of FG-Nups in Nucleocytoplasmic Trafficking
Eleven of the approximately 30 proteins in the yeast NPC are characterized by repeats of Phe-Gly (FG). These proteins, known collectively as FG-Nups, are found in distinct distributions within the NPC: some are found exclusively on the cytoplasmic face of the NPC, some are only on the nuclear face of the NPC, and others are distributed symmetrically through the pore. The Wente lab is interested in studying the role that different FG-Nups play in distinct transport events, including the import and export of both proteins and RNAs.
Transport Fig 2
The Yeast NPC by the Numbers

~3488: the number of repeats of Phe-Gly in a wild-type yeast NPC. These repeats are found on 11 different proteins, which have from 4 to 49 FG repeats each. All FG-Nups are found in the NPC in multiples of 8.

11 of the ~30 Nups in yeast contain FG repeats

~66 MDa is the mass of the yeast NPC
~5.27 MDa is the mass of just the FG domains in the yeast NPC (for comparison, yeast ribosome is 4.2MDa, and has ~70 different proteins)

500-1000 - the number of molecules estimated to traffic through a single NPC every minute

65 to 182 NPCs per yeast nucleus; NPC number varies during the cell cycle


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