The unravelling of the ubiquitin system.

Today, many scientific discoveries are made using a top-down experimental approach. The ubiquitin system was discovered using a 'classic' bottom-up approach to tackle the question: 'how are cellular proteins selectively degraded?' A simple proteolytic assay, which used a crude cell-extract, was all that was required to address this question; it was followed by fractionation and reconstitution experiments to decipher the role of the components in this multi-step process. This 'biochemistry at its best' approach, which was published in a periodical that today would not be regarded as highly visible, provided magnificent findings.