Assembly line inspection

摘要

The cell's macromolecular machines contain dozens or even hundreds of components. But unlike man-made machines, which are built on assembly lines, these cellular machines assemble spontaneously from their protein and nucleic-acid components. It is as though cars could be manufactured by merely tumbling their parts onto the factory floor. Knowing how cellular complexes organize themselves is crucial for understanding molecular evolution and for engineering materials that can mimic their properties. In this issue, Talkington and colleagues (page 628) use isotopically labelled proteins and mass spec-trometry to follow the assembly of one macro-molecular complex — the 30S ribosome — in real time. The elegance of their experimental design should allow it to be adapted to a wide range of such complexes, offering a new approach to the study of cellular dynamics.