Observing proteins in their natural habitat: the living cell

Fluorescence microscopy has played a tremendous role in uncovering the morp hological features of cells and the expression pattern of proteins by immun ofluorescence. Since the discovery of green-fluorescent proteins (GFPs), th is technique has undergone a revival in the life sciences as the spatial di stribution of ectopically expressed fusion proteins inside living cells can now be followed more easily, By further exploiting the photophysical prope rties of the emitted fluorescence with microspectroscopic methods, spatial information on the biochemical parameters of intracellular processes and re actions can be obtained. This possibility will not only play an important r ole in the understanding of biochemical reactions in signal processing and fidelity but also help to uncover the molecular mechanisms of organelle and cell morphogenesis.