Guanine nucleotide exchange factors,

Cyclic AMP-binding Guanine Nucleotide Exchange Factors... 

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. 

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. 

Rowlands, A. G., Panniers, R., and Henshaw, E. C. (1988). The catalytic mechanism of guanine nucleotide exchange factor action and competitive inhibition by phosphorylated eukaryotic initiation factor 2.J. Biol. Chem. 263, 5526-5533. 

Yang, W., and i linnebuscli, A. G. (1996). Identification of a regulatory subcomplex in the guanine nucleotide exchange factor eIF2B that mediates inhibition by phosphorylated eIF2. Mol. Cell Biol. 16, 6603—6616. 

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