Sci. Signal., 11 November 2008
Protein Stability Protein Lifetimes
L. Bryan Ray
Science, Science Signaling, AAAS, Washington, DC 20005, USA
Advances in microarray technologies have focused attention on the regulation of cellular processes by transcriptional control mechanisms. But translation and regulated protein degradation can be equally important parameters in determining physiological effects of proteins (see the Perspective by Grabbe and Dikic). Yen et al. and Yen and Elledge have monitored the lifetime of thousands of individual proteins under various physiological or pathological conditions that can be reproduced in cell culture. The trick is to use a reporter construct having a single promoter that encodes two protein transcripts produced in equal amounts. One is red fluorescent protein and the second is the protein (whose stability you want to know) tagged with a green fluorescent label. The red fluorescent protein is stable, and thus the ratio of fluorescence of the two proteins gives a measure of the stability of the protein being examined. Fluorescence-activated cell sorting is used to separate cells bearing proteins of a particular half-life, and the encoding genes carried in the cells are then identified by polymerase chain reaction. The method has identified previously unrecognized substrates for E3 ubiquitin ligases, which function in control of processes including the cell division cycle, cellular signaling, and apoptosis.
Citation: L. B. Ray, Protein Lifetimes. Sci. Signal. 1, ec388 (2008).
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