Fluorescent tags of protein function in living cells

A cell's biochemistry is now known to be the biochemistry of molecular mach ines, that is, protein complexes that are assembled and dismantled in parti cular locations within the cell as needed. One important element in our und erstanding has been the ability to begin to see where proteins are in cells and what they are doing as they go about their business. Accordingly, ther e is now a strong impetus to discover new ways of looking at the workings o f proteins in living cells. Although the use of fluorescent tags to track i ndividual proteins in cells has a long history, the availability of laser-b ased confocal microscopes and the imaginative exploitation of the green flu orescent protein from jellyfish have provided new tools of great diversity and utility. It is now possible to watch a protein bind its substrate or it s partners in real time and with submicron resolution within a single cell. The importance of processes of self-organisation represented by protein fo lding on the one hand and subcellular organelles on the other are well reco gnised. Self-organisation at the intermediate level of multimeric protein c omplexes is now open to inspection. (C) 2000 John Wiley & Sons, Inc.