Nucleotide exchange factor

Cyclic AMP-binding Guanine Nucleotide Exchange Factors... 

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

A nucleotide exchange factor that activates Ras in response to external cues such as growth factors. Localizes to activated receptors, which contain intrinsic tyrosine kinases, through its interaction with the adaptor protein Grb-2. 

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. 

Guanine nucleotide exchange factors other than hSos have also been found to activate Ras, as have other effectors (see Table 8.2). These may interact with unique sequences in the effector loop. The question remains, however, as to how many different effectors can attach to activated Ras and what determines the level of their priority. 

Gomez, E., Mohammad, S. S., and Pavitt, G. D. (2002). Characterization of the minimal catalytic domain within eIF2B The guanine-nucleotide exchange factor for translation initiation. EMBO J. 21, 5292-5301. 

Goss, D. J., Parkhurst, L. J., Mehta, H. B., Woodley, C. L., and Wahba, A.J. (1984). Studies on the role of eukaryotic nucleotide exchange factor in polypeptide chain initiation. 

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