Research ArticleCell Biology

Triple-Color FRET Analysis Reveals Conformational Changes in the WIP-WASp Actin-Regulating Complex

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Science Signaling  24 Jun 2014:
Vol. 7, Issue 331, pp. ra60
DOI: 10.1126/scisignal.2005198

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WhIPping WASp into Shape

Changes in the actin cytoskeleton in T cells in response to T cell receptor (TCR) activation are mediated by a complex consisting of WIP, an actin-binding protein, and WASp, a protein that promotes actin nucleation. Through a fluorescence resonance energy transfer–based study that visualized protein-protein interactions in live cells, Fried et al. revealed a two-way, end-to-end interaction between WIP and WASp. In response to TCR stimulation, one of the interactions between WIP and WASp was lost, but the other interaction remained, resulting in a conformation-induced increase in activity that stimulated actin polymerization. The conformational change also enabled the ubiquitylation and degradation of WASp to inhibit activity of the complex. Thus, the conformational change functioned as both the on and off switch.