GTPases signalling pathways

Inoue T, Heo WD, Grimley JS, Wandless TJ, Meyer T. An inducible translocation strategy to rapidly activate and inhibit small GTPase signaling pathways. Nat. Methods 2005 2 415-418. 

The intracellular mechanisms that relay glutamate receptor activation to transcription constitute a much-studied field. Small, monomeric GTPases are important activators or silencers of signaling pathways that lead to changes in gene transcription. A final step in these pathways is the activation of transcription factors that cause initiation of transcription. 

Up to 30% of cancers Involve mutations ofRas, a small GTPase that regulates the cell cycle and cellular signaling pathways In response to growth factors (see Chapter 14). 

Fig. 9.1. The Ras protein as a central switching station of signaling pathways. A main pathway for Ras activation is via receptor tyrosine kinases, which pass the signal on via adaptor proteins and guanine nucleotide exchange factors to the Ras protein. Activation ofRas protein can also be initiated via G-protein-coupled receptors and via transmembrane receptors with associated tyrosine kinase activity. The membrane association of the Ras protein (see Fig. 9.6) is not shown for clarity. In addition, not aU signahng pathways that contribute to activation of the Ras protein are shown, nor are all effector reactions. Py omplex of the heterotrimeric G proteins GAP GTPase activating protein GEF guanine nucleotide exchange factor.

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