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Autoinhibited state of the Ras-specific exchange factor RasGRP1Autoinhibited state of the Ras-specific exchange factor RasGRP1
Structural highlights
DiseaseGRP1_HUMAN Disease susceptibility is associated with variations affecting the gene represented in this entry. Aberrantly spliced isoforms and/or diminished levels of RASGRP1 are found in a cohort of SLE patients raising the possibility that dysregulation of this signaling protein contributes to the development of autoimmunity in a subset of SLE patients. FunctionGRP1_HUMAN Functions as a diacylglycerol (DAG)-regulated nucleotide exchange factor specifically activating Ras through the exchange of bound GDP for GTP. Activates the Erk/MAP kinase cascade. Couples T-lymphocytes and B-lymphocytes antigen receptors to the activation of Ras. Hence, regulates T-cells and B-cells development, homeostasis and differentiation. Functions also in FcERI-evoked degranulation and cytokine secretion by mast cells, regulating allergic responses. May also function in other cell types differentiation.[1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedRasGRP1 and SOS are Ras-specific nucleotide exchange factors that have distinct roles in lymphocyte development. RasGRP1 is important in some cancers and autoimmune diseases but, in contrast to SOS, its regulatory mechanisms are poorly understood. Activating signals lead to the membrane recruitment of RasGRP1 and Ras engagement, but it is unclear how interactions between RasGRP1 and Ras are suppressed in the absence of such signals. We present a crystal structure of a fragment of RasGRP1 in which the Ras-binding site is blocked by an interdomain linker and the membrane-interaction surface of RasGRP1 is hidden within a dimerization interface that may be stabilized by the C-terminal oligomerization domain. NMR data demonstrate that calcium binding to the regulatory module generates substantial conformational changes that are incompatible with the inactive assembly. These features allow RasGRP1 to be maintained in an inactive state that is poised for activation by calcium and membrane-localization signals. DOI:http://dx.doi.org/10.7554/eLife.00813.001. Structural analysis of autoinhibition in the Ras-specific exchange factor RasGRP1.,Iwig JS, Vercoulen Y, Das R, Barros T, Limnander A, Che Y, Pelton JG, Wemmer DE, Roose JP, Kuriyan J Elife. 2013 Jul 30;2:e00813. doi: 10.7554/eLife.00813. Print 2013. PMID:23908768[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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