The N-terminal pleckstrin, coiled-coil, and IQ domains of the exchange factor Ras-GRF act cooperatively to facilitate activation by calcium
- PMID: 8756648
- PMCID: PMC231491
- DOI: 10.1128/MCB.16.9.4888
The N-terminal pleckstrin, coiled-coil, and IQ domains of the exchange factor Ras-GRF act cooperatively to facilitate activation by calcium
Abstract
We have recently shown that the neuronal exchange factor p140 Ras-GRF becomes activated in vivo in response to elevated calcium levels [C. L. Farnsworth, N. W. Freshney, L. B. Rosen, A. Ghosh, M. E. Greenberg, and L. A. Feig, Nature (London) 376:524-527, 1995]. Activation is mediated by calcium-induced calmodulin binding to an IQ domain near the N terminus of Ras-GRF. Here we show that the adjacent N-terminal pleckstrin homology (PH), coiled-coil, and IQ domains function cooperatively to allow Ras-GRF activation. Deletion of the N-terminal PH domain redistributes a large percentage of Ras-GRF from the particulate to the cytosolic fraction of cells and renders the protein insensitive to calcium stimulation. A similar cellular distribution and biological activity are observed when only the core catalytic domain is expressed. Although the PH domain is necessary for particulate association of Ras-GRF, it is not sufficient for targeting the core catalytic domain to this cellular location. This requires the PH domain and the adjacent coiled-coil and IQ sequences. Remarkably, this form of Ras-GRF is constitutively activated. The PH and coiled-coil domains must also perform an additional function, since targeting to the particulate fraction of cells is not sufficient to allow Ras-GRF activation by calcium. A Ras-GRF mutant containing the PH domain from Ras-GTPase-activating protein in place of its own N-terminal PH domain localizes to the particulate fraction of cells but does not respond to calcium. Similar phenotypes are seen with mutant Ras-GRFs containing point mutations in either the PH or coiled-coil domain. These findings argue that the N-terminal PH, coiled-coil, and IQ domains of Ras-GRF function together to connect Ras-GRF to multiple components in the particulate fractions of cells that are required for responsiveness of the protein to calcium signaling.
Similar articles
-
Domain contributions to signaling specificity differences between Ras-guanine nucleotide releasing factor (Ras-GRF) 1 and Ras-GRF2.J Biol Chem. 2014 Jun 6;289(23):16551-64. doi: 10.1074/jbc.M114.557959. Epub 2014 Apr 22. J Biol Chem. 2014. PMID: 24755227 Free PMC article.
-
Activation of the exchange factor Ras-GRF by calcium requires an intact Dbl homology domain.FEBS Lett. 1997 Apr 21;407(1):111-5. doi: 10.1016/s0014-5793(97)00309-8. FEBS Lett. 1997. PMID: 9141492
-
Ras-specific exchange factor GRF: oligomerization through its Dbl homology domain and calcium-dependent activation of Raf.Mol Cell Biol. 1999 Jul;19(7):4611-22. doi: 10.1128/MCB.19.7.4611. Mol Cell Biol. 1999. PMID: 10373510 Free PMC article.
-
Guanine nucleotide exchange factors: activators of Ras superfamily proteins.Mol Reprod Dev. 1995 Dec;42(4):468-76. doi: 10.1002/mrd.1080420415. Mol Reprod Dev. 1995. PMID: 8607978 Review.
-
Control of ras activation.Cancer Surv. 1996;27:87-100. Cancer Surv. 1996. PMID: 8909796 Review.
Cited by
-
Scaffold proteins IRSp53 and spinophilin regulate localized Rac activation by T-lymphocyte invasion and metastasis protein 1 (TIAM1).J Biol Chem. 2010 Jun 4;285(23):18060-71. doi: 10.1074/jbc.M109.051490. Epub 2010 Apr 1. J Biol Chem. 2010. PMID: 20360004 Free PMC article.
-
Ras guanine nucleotide releasing factor 1 (RasGrf1) enhancement of Trk receptor-mediated neurite outgrowth requires activation of both H-Ras and Rac.J Mol Neurosci. 2013 Jan;49(1):38-51. doi: 10.1007/s12031-012-9847-9. Epub 2012 Jun 29. J Mol Neurosci. 2013. PMID: 22744634
-
Domain contributions to signaling specificity differences between Ras-guanine nucleotide releasing factor (Ras-GRF) 1 and Ras-GRF2.J Biol Chem. 2014 Jun 6;289(23):16551-64. doi: 10.1074/jbc.M114.557959. Epub 2014 Apr 22. J Biol Chem. 2014. PMID: 24755227 Free PMC article.
-
Structural and spatial determinants regulating TC21 activation by RasGRF family nucleotide exchange factors.Mol Biol Cell. 2009 Oct;20(20):4289-302. doi: 10.1091/mbc.e09-03-0212. Epub 2009 Aug 19. Mol Biol Cell. 2009. PMID: 19692568 Free PMC article.
-
p35/cyclin-dependent kinase 5 phosphorylation of ras guanine nucleotide releasing factor 2 (RasGRF2) mediates Rac-dependent Extracellular Signal-regulated kinase 1/2 activity, altering RasGRF2 and microtubule-associated protein 1b distribution in neurons.J Neurosci. 2004 May 5;24(18):4421-31. doi: 10.1523/JNEUROSCI.0690-04.2004. J Neurosci. 2004. PMID: 15128856 Free PMC article.
References
MeSH terms
Substances
LinkOut - more resources
Full Text Sources