Strategies to investigate protein turnover with fluorescent protein reporters in eukaryotic organisms

In higher eukaryotes, defects in regulated protein turnover are intimately linked to development of diseases and aging. Systematic investigation of proteostasis and protein degradation pathways is of high importance for understanding basic cellular events as well as developmental processes in higher organisms. Recently, novel fluorescent protein-based tools for monitoring protein degradation and mapping degradation pathways were described that facilitate this task. Here we give an overview of these tools and relate them to biophysical properties of fluorescent proteins. We focus on methods for the identification of degradation pathways, the discovery of novel degradation sequences, the investigation of proteome dynamics, and the characterization of protein stability. One can expect systematic application of these tools in the near future by systems biology approaches enhancing understanding of the ubiquitin-proteasome system from single protein degradation pathways to its influence on developmental processes.