New research supports model for nuclear pore complex

August 18, 2009

(PhysOrg.com) -- To protect their DNA, cells in higher organisms are very choosy about what they allow in and out of their nuclei, where the genes reside. Guarding access is the job of transport machines called nuclear pore complexes, which stud the nuclear membrane. Despite these gatekeepers’ conspicuously large size (they are made of 30 different proteins), they have proved largely inscrutable to researchers over the years. But bit by bit, scientists are learning how these machines work.

Now a new study reveals the structure of one of the proteins that makes up this molecule-trafficking complex. Researchers have also shown how that interacts with a partner, supporting a model that calls for a flexible “ring” around the opening of each pore. The work could offer a key insight into an important design feature of this little-understood and evolutionarily ancient structure, an innovation fundamental to the development of nearly all multicellular life on Earth.

The research, performed by Hyuk-Soo Seo, a postdoctoral associate, and André Hoelz, a research associate, both in Rockefeller University’s Laboratory of Cell Biology, determined the molecular structure of the only remaining unsolved protein in an important piece of the nuclear pore called the Nup84 complex. Nup84 is a Y-shaped element that was recently imaged in three dimensions by Martin Kampmann, also a member of the lab headed by Howard Hughes Medical Institute Investigator Günter Blobel.

In experiments published online last week in the Proceedings of the National Academy of Sciences, Seo, Hoelz and colleagues focused on the behavior of this newly solved protein — or nucleoporin — called Nup120, one of seven comprising the Nup84 complex. They determined that one end of Nup120, the N-terminal domain, is attached by a stretchable tether to one other protein in the complex, Nup133. Furthermore, the researchers showed in living cells that mutations to a critical region of the tether interfered with the export of messenger RNA, one of the nuclear pore’s chief responsibilities, confirming the functional importance of this loose linkage between the two proteins.

“It’s a very nice correlation from the structure to the function,” Hoelz says. “It’s the first example where we can really pin down how the [Nup84] complexes arrange with each other, and what we believe we see is a flexible ring that could expand and contract to import and export large .”

More information: Proceedings of the National Academy of Sciences online: August 11, 2009; Structural and functional analysis of Nup120 suggests ring formation of the Nup84 complex; Hyuk-Soo Seo, Yingli Ma, Erik W. Debler, Daniel Wacker, Stephan Kutik, Günter Blobel, and André Hoelz

Provided by Rockefeller University (news : web)

Explore further: Building the nuclear pore piece by piece

Related Stories

Building the nuclear pore piece by piece

April 16, 2007

The nuclear pore complexes are the sole gatekeepers for the cell’s nucleus — proteins, RNA, viruses, anything that passes between the nucleus and the rest of the cell has to use one of these giant protein assemblies. ...

Recommended for you

Smarter brains are blood-thirsty brains

August 30, 2016

A University of Adelaide-led project has overturned the theory that the evolution of human intelligence was simply related to the size of the brain—but rather linked more closely to the supply of blood to the brain.

Defend or grow? These plants do both

August 30, 2016

From natural ecosystems to farmers' fields, plants face a dilemma of energy use: outgrow and outcompete their neighbors for light, or defend themselves against insects and disease.

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.