Structural analysis of autoinhibition in the Ras-specific exchange factor RasGRP1

Elife. 2013 Jul 30;2:e00813. doi: 10.7554/eLife.00813.

Abstract

RasGRP1 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.

Keywords: Human; cell signaling; diacylglycerol; nucleotide exchange factor.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Calcium / metabolism
  • Crystallography, X-Ray
  • DNA-Binding Proteins / antagonists & inhibitors
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism*
  • Guanine Nucleotide Exchange Factors / antagonists & inhibitors
  • Guanine Nucleotide Exchange Factors / chemistry
  • Guanine Nucleotide Exchange Factors / metabolism*
  • Humans
  • Models, Molecular
  • Molecular Sequence Data
  • Nuclear Magnetic Resonance, Biomolecular
  • Protein Conformation
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Sequence Homology, Amino Acid

Substances

  • DNA-Binding Proteins
  • Guanine Nucleotide Exchange Factors
  • RASGRP1 protein, human
  • Recombinant Proteins
  • Calcium