Editors' ChoiceMethodology

Following Protein Activation in Real Time

Science's STKE  27 Mar 2001:
Vol. 2001, Issue 75, pp. tw3
DOI: 10.1126/stke.2001.75.tw3

Fluorescence resonance energy transfer (FRET) is emerging as a powerful tool that allows real-time monitoring of protein interactions in living cells. Janetopoulos et al. added fluorescent tags to the Gα2 and Gβ subunits of heterotrimeric guanine nucleotide binding proteins (G proteins) in Dictyostelium discoideum. The G protein-coupled receptors are a very large family of proteins that mediate the action of hormones, neurotransmitters, and other signaling molecules. In this case, the authors treated cells with a chemoattractant and then observed the dissociation of the active G protein subunits by FRET. During continuous stimulation, the physiological response to the chemoattractant subsided, but the G protein remained activated (as measured by dissociation of the heterotrimer). The authors suggest that signal adaptation must occur downstream of the activated G protein. The method is expected to be extensible to mammalian cells and should enable substantial improvement in our quantitative understanding of mechanisms of G protein signaling.

C. Janetopoulos, T. Jin, P. Devreotes, Receptor-mediated activation of heterotrimeric G-proteins in living cells. Science 291, 2408-2411 (2001). [Abstract] [Full Text]