"To carry out their tasks, most proteins work in dynamic complexes that may contain dozens of molecules," says Giulio Superti-Furga, who launched the large-scale project at Cellzome four years ago. "If you think of the cell as a factory floor, up to now, we've known some of the components of a fraction of the machines. That has seriously limited what we know about how cells work. This study gives us a nearly complete parts list of all the machines, and it goes beyond that to tell us how they populate the cell and partition tasks among themselves."
The study combined a method of extracting complete protein complexes from cells (tandem affinity purification, developed in 2001 by Bertrand Sraphin at EMBL), mass spectrometry and bioinformatics to investigate the entire protein household of yeast, turning up 257 machines that had never been observed. It also revealed new components of nearly every complex already known.
In the course of the work, new computational techniques were developed at EMBL that gave new insights into the dynamic nature of protein complexes. In contrast to most man-made factories, cells continually dismantle and reassemble their machines at different stages of the cell cycle and in response to environmental challenges, such as infections.
"This would be a logistical nightmare if the cell had to build every machine from scratch any time it needed to do something," says Anne-Claude Gavin, former Director of Molecular and Cell Biology at Cellzome and currently a team leader at EMBL. "We've discovered that the reality is different. Cells use a mixed strateg
Contact: Anna-Lynn Wegener
European Molecular Biology Laboratory