Plate Nº 79 · recorded November 12, 2026
Biology & EvolutionReported finding
Glowing Dyes Show Nuclear Pores Run Like Liquids, Not Gummy Bears
Fluorescent dyes reveal that the barrier inside living human nuclear pores is fluid, kept liquid by sugar groups and transport receptors — with implications for neurodegeneration.
By James Calloway4 min read790 words
In brief
- Researchers measured protein dynamics inside living human nuclear pores for the first time, finding the barrier is fluid-like.
- In test tubes the same proteins hardened into gummy-bear-like solids after about two hours; in living cells they stayed mobile.
- A transport receptor plus glycosylation (sugar groups) keeps the barrier from stiffening.
- Simulations on JUPITER, Europe's first exascale supercomputer, confirm transport runs mainly along the pore's edge.
- Published in Nature (2026), DOI 10.1038/s41586-026-11258-0.
Researchers have, for the first time, measured protein dynamics inside the nuclear pores of living human cells — and found the barrier that guards our genome behaves like a fluid, not a gel. The finding, published in Nature, comes from a team at Johannes Gutenberg University Mainz (JGU), the Max Planck Institute for Biophysics (MPI-BP) in Frankfurt and Wuhan University in China.
"For the first time, we have been able to measure intrinsic protein dynamics within the nanocanal of a living cell and demonstrate that the interior of this canal is fluid-like," said Edward Lemke, professor of synthetic biophysics at JGU, who co-led the study with Gerhard Hummer of the MPI-BP.
What is a nuclear pore?
Our DNA sits inside the nucleus, wrapped in a double membrane. Nothing strolls through that membrane freely. Every molecule must use one of several thousand nuclear pores — gate-like machines that each process tens of thousands of molecular visitors per minute. Some are waved through. Others are turned away, like travelers at a medieval town gate.
Scientists knew the pore's scaffold structure, and they knew a protein mesh fills the opening and does the selecting. What they argued about was texture. Was that barrier a stretch of rigid polymers? A liquid-like condensate? Or something solid, with the consistency of a gummy bear? Studies on isolated proteins in test tubes pointed in all three directions at once.
That ambiguity had a simple cause. "Such studies did not, however, allow any direct conclusions to be drawn about how the barrier behaves within the living cell," said Lemke.
How do you watch a protein inside a living pore?
Lemke's team attached fluorescent dyes to the pore proteins — tiny glowing probes whose movement betrays how the proteins behave. Fast-moving dyes mean a fluid environment. "As the dyes move extremely quickly, the state inside the nuclear pores must be fluid-like," said Lemke.
The proteins stayed highly mobile for the full two-hour observation window. The test-tube comparison told a different story. In the in vitro model, the same protein mass reliably stiffened after roughly two hours — first into that "gummy bear" solid, then into deposits resembling those found in the brains of people with Alzheimer's or Parkinson's disease.
"This was a crucial turning point: there had to be something keeping the barrier in the cells dynamic," said Lemke.
Two ingredients turned out to do the trick:
- A transport receptor that keeps traffic moving.
- Glycosylation — sugar groups attached to the barrier proteins — which stops them from sticking together too tightly.
"When we add these two components, we observe a similar mobility in the model system to that found in the nuclear pores of living cells," said Lemke.
Why does cargo hug the edges?
The study also tackled the transport route itself. In a pipe or a river, flow runs fastest in the center. In nuclear pores, earlier work suggested the opposite: cargo moves along the rim. Many assumed a biological reason — perhaps a plug clogging the pore's center.
Hummer's team built the most comprehensive nuclear pore simulation to date, using the degree of protein cross-linking measured in Mainz. The model ran on JUPITER, Europe's first exascale supercomputer at the Jülich Research Center.
"The simulations confirm that the main transport route runs along the edge of the pore," said Hummer. "While we do not rule out a biological cause such as a plug, it is not necessary from a physicochemical point of view."
So no exotic plug is required. Physics alone explains the rim traffic — at least in the model. Simulations are simulations; live-cell confirmation of the pathway remains the obvious next hurdle.
What does this change for medicine?
"As the nuclear pore protects the genome and controls all exchange between the cell nucleus and the cytoplasm, it is one of the most important molecular machines in the human cell," said Miao Yu of Wuhan University, co-first author of the study. "And also one of the most complex," added co-first author Maziar Heidari of the MPI-BP.
The practical payoff may lie in neurodegeneration. Alzheimer's and Parkinson's both involve once-flexible proteins hardening into deposits — exactly the transition the test-tube barrier underwent without its sugar groups and transport receptor. Understanding what keeps the natural barrier liquid could inform how that stiffening goes wrong.
Be clear about limits. This is one study, in cells, with dye probes and computer models. It settles the fluid-versus-gel debate for the pore barrier and nothing more. The paper is Miao Yu et al., "Glycosylation and importins liquefy the FG barrier in live nuclear pores," Nature (2026), DOI: 10.1038/s41586-026-11258-0.
via phys.org/rss-feed/ (Source)
More from James Calloway
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Staff writer covering regulation, policy and their impact on general science news at SciBeat.
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