Nucleotides Guanine

Pai, E.F., et al. Structure of the guanine-nucleotide-binding domain of the Ha-ras oncogene product p21 in the triphosphate conformation. Nature 341 209-214,... 

Cyclic AMP-binding Guanine Nucleotide Exchange Factors... 

Guanine Nucleotide Dissociation Inhibitors. Small GTPases... 

Guanine nucleotide dissociation inhibitors (GDIs) bind to small GTPases and inhibit the dissociation and thus the exchange of the bound nucleotide. 

Guanine nucleotide exchange factors (GEFs) are proteins which catalyse the release of nucleotide bound to small GTPases. 

Vav proteins are guanine nucleotide exchange factors (GEF) for monomeric GTPases. Tire Vav proteins belong to the DBL family of Rho GEFs and have an important role in regulating early events in receptor signalling. 

Figure 1. Simplified schematic of receptor-mediated signal transduction in neutrophils. Binding of ligand to the receptor activates a guanine-nucleotide-binding protein (G protein), which then stimulates phospholipase C. Phosphatidylinositol 4,5-bis-phosphate is cleaved to produce diacylglycerol (DAG) and inositol 1,4,5-trisphosphate (IP3). DAG stimulates protein kinase C. IP3 causes the release of Ca from intracellular stores, which results in an increase in the cytosolic Ca concentration. This increase in Ca may stimulate protein kinase C, calmodulin-dependent protein kinases, and phospholipase A2. Protein phosphorylation events are thought to be important in stimulating degranulation and oxidant production. In addition, ionic fluxes occur across the plasma membrane. It is possible that phospholipase A2 and ionic channels may be governed by G protein interactions. ...

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