This molecular sculptor may have molded and re-formed the outer cell membrane of primitive bacteria into the intricate and interconnected protein transport network inside cells that is essential for the function of cells ranging from yeast to plants to humans.

This transportation network, called the endomembrane system, and the presence of a nucleus that contains the cell's DNA, are among the features that distinguish eukaryotic cells -- which make up plants, animals and humans -- from the prokaryotic cells that make up bacteria.

Reporting in PLoS Biology, Rout, together with Rockefeller colleague Brian T. Chait, D.Phil., and Andrej Sali, Ph.D., a former Rockefeller scientist now at University of California, San Francisco, describes a three-dimensional sketch of a core building block found in a structure called the nuclear pore complex (NPC) in eukaryotic cells. A massive complex of proteins, the NPC serves as a checkpoint between the cell's nucleus and the surrounding soupy cytoplasm inside the cell. Small molecules can enter and exit the nucleus through the NPC at will, but larger proteins and RNA molecules are allowed entry selectively.

"Buried in the NPC is a fossil indicating what it evolved from," says Rout, assistant professor and head of the Laboratory of Structural and Cell Biology at Rockefeller. "And we believe the job of this fossil is similar to its progenitor -- namely to curve membranes."

This discovery gives scientists a significant insight into the evolution of eukaryotes, or cells that carry their DNA inside a nucleus. "By manipulating, shaping and pulling in a membrane, cells could create tiny compartments that perform many of the
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Contact: Joseph Bonner
bonnerj@rockefeller.edu
212-327-8998
Rockefeller University
4-Nov-2004