The problem
A cell keeps its DNA inside the nucleus, but proteins must enter and RNA messages must leave so the cell can use that information. Openings called nuclear pores control this traffic. How does the flexible material inside a pore favor particular molecules without simply sealing the passage?[2]
The nucleus holds cellular DNA, while many proteins enter it and RNA leaves through nuclear pores. How does the material inside a pore selectively permit traffic? Flexible protein segments with phenylalanine–glycine repeats, called FG domains, interact with transport factors such as karyopherins. In isolated yeast pores, removing associated factors altered a mobile central cluster called the central plug; adding the import factor Kap95 restored a plug-like structure, but with faster dynamics than the original. That comparison ties organization to molecular interactions without resolving the full native mixture or every species.[1] [2]
Scope
Molecular organization and cargo-dependent behavior of the nuclear-pore central barrier, especially the karyopherin-associated central plug characterized in yeast.
What remains open
The 2025 imaging result constrains its organization. It leaves molecular structure, cargo-dependent adaptation and generality across species incomplete.[1]
Why it matters
Separating DNA from the rest of the cell is useful only if the right molecules can still cross the boundary. The pore makes that separation compatible with gene activity: proteins needed inside can enter, and RNA can carry information out for protein production.[2]
A boundary that indiscriminately excludes molecules would obstruct gene expression; one that indiscriminately admits them would undermine compartmental control. The changing pore barrier helps reconcile exchange with separation. Linking its interactions to selectivity also clarifies what laboratory models of a pore must reproduce before their behavior can explain transport in a living nucleus.[1] [2]
Definitions
3 terms
Karyopherin
A nuclear transport factor that binds suitable cargo and interacts with pore proteins to support passage. Particular factors also contribute to barrier organization; this is not the route for every RNA or protein.[1] [2]
FG domain
A flexible region of a pore protein containing repeated phenylalanine–glycine sequences. Its interactions with other regions and transport factors contribute to the selective barrier.[1] [2]
Central plug
A mobile central cluster observed in the nuclear-pore channel, especially characterized here in yeast. The name does not mean an immovable stopper or a completely resolved molecular structure.[1]
Sources
- Karyopherins remodel the dynamic organization of the nuclear pore complex transport barrier
Notes on Karyopherins remodel the dynamic organization of the nuclear pore complex transport barrier
Yeast pore imaging and factor reconstitution constrain a dynamic central barrier. Kap95 restores a plug-like structure with different dynamics; molecular mixture, cargo adaptation and cross-species scope remain incomplete.
- The role of phase separation for RNA and protein transport through the nuclear pore complex
Notes on The role of phase separation for RNA and protein transport through the nuclear pore complex
Review explains why nuclear separation needs selective protein/RNA exchange and compares flexible-barrier models. The verified June 2025 review predates the December yeast study and cannot itself support that later result.