There are ribosomes in nearly every living cell, translating the genetic code of DNA into working proteins. The complicated architecture of this large globule of more than 50 proteins and several ribonucleic acids (RNAs) has proved difficult to unravel.

Now Harry Noller and his colleagues of the University of California at Santa Cruz have worked out the first complete, fine-detailed structure of this two-subunit protein factory. Although the structures of the ribosome's two separate units were already known, the new map shows the whole picture -- including the hollow between them, where protein production occurs.

"Now we can see new aspects of the structures that weren't visible before," says Peter Moore of Yale University in Connecticut, whose own group solved the atomic structure of the large subunit last year2. Noller's map is less detailed than Moore's, but it provides a framework on which previous maps can be pieced together. "It's generated enormous excitement," says Moore.

"People have been arguing about this for 50 years," says Roger Garrett, of Copenhagen University in Denmark who spent 35 years trying to unravel the ribosome before giving up. Efforts are now focusing on how the protein machine actually runs. "This is an entry into a new phase, like when the first enzyme structure was discovered," says Garrett. "Now we can go in and see how it all works on a molecular level."

A large number of antibiotics disable bacteria by binding to sites on the bacterial ribosome to stop it producing proteins. Thus insights into ribosome structure may lead to improvements in antibiotic design. "Now we know how antibiotics fit into the structure we have a molecular basis for improving them," says Garrett.

"It's the hope of many pharmaceutical companies," agrees Venki Ramakrishnan of the Medical Research Council Laboratory of Molecular Biology in Cambridge, UK. His group is working out how the ribosome can read and translate the genetic code so accurately; they hope to publish their findings very soon.