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Characterisation of PDZ-GEFs, a family of guanine nucleotide exchange factors specific for Rap1 and Rap2

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Rehmann,  Holger
Max Planck Institute of Molecular Physiology, Max Planck Society;

http://pubman.mpdl.mpg.de/cone/persons/resource/persons98738

Wittinghofer,  Alfred
Sonstige Wissenschaftliche Organisationseinheiten, Max Planck Institute of Molecular Physiology, Max Planck Society;

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Citation

Kuiperij, H. B., De Rooij, J., Rehmann, H., van Triest, M., Wittinghofer, A., Bos, J. L., et al. (2003). Characterisation of PDZ-GEFs, a family of guanine nucleotide exchange factors specific for Rap1 and Rap2. Biochimica et Biophysica Acta - Molecular Cell Research, 1593(2-3): 1, pp. 141-149. Retrieved from http://dx.doi.org/10.1016/S0167-4889(02)00365-8.


Cite as: http://hdl.handle.net/11858/00-001M-0000-0014-0CB2-C
Abstract
PDZ-GEF1 (RA-GEF/nRapGEP/CNrasGEF) is a guanine nucleotide exchange factor (GEF) characterised by the presence of a PSD- 95/DlgA/ZO-1 (PDZ) domain, a Ras-association (RA) domain and a region related to a cyclic nucleotide binding domain (RCBD). These domains are in addition to a Ras exchange motif (REM) and GEF domain characteristic for GEFs for Ras-like small GTPases. PDZ-GEF1 efficiently exchanges nucleotides of both Rap I and Rap2, but has also been implicated in mediating cAMP-induced Ras activation through binding of cAMP to the RCBD. Here we describe a new family member, PDZ-GEF2, of which we isolated two splice variants (PDZ-GEF2A and 213). PDZ-GEF2 contains, in addition to the domains characteristic for PDZ-GEF1, a second, less conserved RCBD at the N-terminus. PDZ-GEF2 is also specific for both Rap I and Rap2. We further investigated the possibility that PDZ-GEF2, like PDZ-GEF1, is a cAMP-responsive GEF for Ras. However, in contrast to previous results, we did not find any effect of either PDZ-GEF1 or PDZ-GEF2 on Ras in the absence or presence of cAMP. Moreover, affinity measurements by isothermic calorimetry showed that the RCBD of PDZ-GEF1 does not bind cAMP with a physiologically relevant affinity. We conclude that both PDZ-GEF1 and 2 are specific for Rap1 and Rap2 and unresponsive to cAMP and various other nucleotides. (C) 2002 Elsevier Science B.V. All rights reserved.