Editors' ChoiceSmall GTP-binding proteins

From Ras to Rac

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Science's STKE  28 Sep 1999:
Vol. 1999, Issue 1, pp. tw4
DOI: 10.1126/stke.1999.1.tw4

Cytoskeletal rearrangements can occur when cells respond to certain extracellular stimuli. One of the signaling cascades implicated in this process involves communication between the small GTP-binding proteins Ras and Rac. Scita et al. now show that fibroblast cell lines derived from knockout mice that lack the protein Eps8 do not remodel actin when treated with growth factors. Rac activity was regulated by a complex containing the proteins Eps8, E3b1, and Sos-1. The authors suggest that the formation of this complex stimulates the Rac-GEF activity of Sos-1. In addition, Eps8 activity was localized downstream of phosphatidylinositol 3-phosphate kinase, an immediate downstream effector of Ras. Hence, this complex may facilitate the transfer of signals between Ras and Rac.

Scita, G., Nordstrom, J., Carbone, R., Tenca, P., Giardina, G., Gutkind, S., Bjarnegard, M., Betsholtz, C., and Di Fiore, P.P. (1999) EPS8 and E3B1 transduce signals from Ras to Rac. Nature 401: 290-293. Online Journal