In every cell of higher organisms such as humans and yeast cells, there is a lot of activity at the gates from the center (nucleus) to the environment: 1,000 things of different sizes are checked and passed through per second, explained the Viennese cell biologist Alwin Köhler of the APA. Highly flexible baskets on the inside make this possible. Transported goods slip through here like a ball through a basketball net, he reports with colleagues in the journal “Science Advances”.
A team led by Alwin Köhler from the Max Perutz Labs in Vienna marked the main components of the cell nuclear pore baskets with fluorescent dyes and examined under the microscope how they are assembled on an artificial membrane. The researchers saw that these parts of the nuclear pore have no fixed shape at all, but are made up of “intrinsically disordered” proteins that are extremely flexible, like the tentacles of an octopus.
“In this study, we were able to show for the first time that it is precisely this tentacle-like shape that enables the extremely flexible structure of the nuclear pore baskets,” he explained. A protein (protein) called Nup60 connects the individual components by winding in a tentacle-like manner from one to the other and attaching here and there with Velcro-like sections (short linear motifs – SLiMs).
On the one hand, it weaves a stable structure and, on the other hand, the baskets can quickly expand and contract again in order to let through very small as well as very large molecules. In addition, Nup60 also acts as a “hanging cable” to attach the baskets to the nuclear membrane, the researchers said in a release.
With this structure, the nuclear pore baskets manage to combine two apparently contradictory tasks, said Köhler: to decide highly selectively what is allowed to pass through, and at the same time to ensure mass transport for people of all sizes passing through.