GDP/GTP exchange factor

Alone, P. V., and Dever, T. E. (2006). Direct binding of translation initiation factor eIF2gamma-G domain to its GTPase-activating and GDP—GTP exchange factors eIF5 and eIF2B epsilon. J. Biol. Client. 281, 12636—12644. 

Asano, K., Krishnamoorthy, T., Phan, L., Pavitt, G. D., and Hinnebusch, A. G. (1999). Conserved bipartite motifs in yeast eIF5 and eIF2Bepsilon, GTPase-activating, and GDP—GTP exchange factors in translation initiation, mediate binding to their common substrate eIF2. EMBOJ. 18, 1673—1688. 

Panniers, R., and Henshaw, E. C. (1983). A GDP/GTP exchange factor essential for eukaryotic initiation factor 2 cycling in Ehrlich ascites tumor cells and its regulation by eukaryotic initiation factor 2 phosphorylation. J. Biol. Chem. 258, 7928—7934. 

Gebbink, M. F., Kranenburg, O., Poland, M., van Horck, F. P., Houssa, B., and Moolenaar, W. H. (1997). Identification of a novel, putative Rho-specific GDP/GTP exchange factor and a RhoA-binding protein Control of neuronal morphology. / Cell Biol. 137, 1603-1613. 

Alam MR, Johnson RC, Darlington DN, Hand TA, Mains RE, Eipper BA (1997) Kalirin, a cytosolic protein with spectrin-like and GDP/ GTP exchange factor-like domains that interacts with peptidylgly-cine alpha-amidating monooxygenase, an integral membrane peptide-processing enzyme. J Biol Chem 272 12667-12675. 

Delague V, Jacquier A, Hamadouche T et al (2007) Mutations in fgd4 encoding the rho gdp/gtp exchange factor frabin cause autosomal recessive charcot-marie-tooth type 4 h. Am J Hum Genet 81 1-16... 

GDP-GTP exchange factor Kinase/Phosphatase Small GTP-binding protein ( Transcription factor... 

Charych, E., Yu, W., MiraUes, C., Serwanski, D., Li, X., Rubio, M., and De Bias, A. (2004). The brefeldin A-inhibited GDP/GTP exchange factor 2, a protein involved in vesicular trafficking, interacts with the beta subunits of the GABA receptors. J. Neurochem. 90,... 

Ashery, U., Koch, H., Scheuss, V., Brose, N., and Rettig, J. (1999). A presynaptic role for the ADP ribosylation factor (ARF)-specific GDP/GTP exchange factor msec7-l. Proc. Natl. Acad. Sci. USA 96,1094-1099. 

Should this as yet unproven view be correct, two types of translational inhibitor should be clearly distinguished. The first comprises the various kinases that phosphorylate the a-subunit of eIF-2 and are controlled by heme or activated by dsRNA or other conditions (Section 7.4). These kinases repress translation because they cause elF-2 to be phosphorylated. The second type of inhibitor is phosphorylated eIF-2 itself, which, by competing with active eIF-2 for the GDP/GTP exchange factor, eIF-2B, depletes the pool of recycling eIF-2B as just suggested and prevents recycling of eIF-2. The observation that phosphorylated eIF-2 is able to stimulate translation in heme-deficient lysates (Safer et ai, 1977 Benne et al., 1980) is not at variance with this view, because the observed effect concerns non-catalytic functioning of eIF-2. 

Figure 12.20 The G-protein activation/inactivation cycle. When the G-protein is associated with GTP, it is active when it is associated with GDP it is inactive. The hormone-receptor complex is the GTP exchange factor, which exchanges GDP for GTP to convert the inactive form to the active form. A GTPase activity inactivates the G-protein by hydrolysing GTP.

The first step in the activation of G proteins is the replacement of GDP by GTP. Whereas in the case of heterotrimeric G proteins, GDP-GTP exchange is catalysed by G-protein-coupled heptahelical receptors, monomeric G proteins, such as Ras, recruit GDP exchange factors (GEFs) and guanine nucleotide release proteins (GNRPs). These factors promote formation of the active, GTP-bound form of Ras and, because they are linkers, connect Ras with the RTK. 

Phosphorylated receptor recruits exchange factors Siat stimulate GDP-GTP exchange on Fiaa... 

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