Crystal structure of the Histone domain, DH-PH unit, and catalytic unit of the Ras activator Son of Sevenless (SOS)

Experimental Data Snapshot

  • Resolution: 3.18 Å
  • R-Value Free: 0.312 
  • R-Value Work: 0.259 
  • R-Value Observed: 0.264 

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This is version 1.3 of the entry. See complete history


Role of the histone domain in the autoinhibition and activation of the Ras activator Son of Sevenless.

Gureasko, J.Kuchment, O.Makino, D.L.Sondermann, H.Bar-Sagi, D.Kuriyan, J.

(2010) Proc Natl Acad Sci U S A 107: 3430-3435

  • DOI: https://doi.org/10.1073/pnas.0913915107
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Membrane-bound Ras is activated by translocation of the Son of Sevenless (SOS) protein to the plasma membrane. SOS is inactive unless Ras is bound to an allosteric site on SOS, and the Dbl homology (DH) and Pleckstrin homology (PH) domains of SOS (the DH-PH unit) block allosteric Ras binding. We showed previously that the activity of SOS at the membrane increases with the density of PIP(2) and the local concentration of Ras-GTP, which synergize to release the DH-PH unit. Here we present a new crystal structure of SOS that contains the N-terminal histone domain in addition to the DH-PH unit and the catalytic unit (SOS(HDFC), residues 1-1049). The structure reveals that the histone domain plays a dual role in occluding the allosteric site and in stabilizing the autoinhibitory conformation of the DH-PH unit. Additional insight is provided by kinetic analysis of the activation of membrane-bound Ras by mutant forms of SOS that contain mutations in the histone and the PH domains (E108K, C441Y, and E433K) that are associated with Noonan syndrome, a disease caused by hyperactive Ras signaling. Our results indicate that the histone domain and the DH-PH unit are conformationally coupled, and that the simultaneous engagement of the membrane by a PH domain PIP(2)-binding interaction and electrostatic interactions between a conserved positively charged patch on the histone domain and the negatively charged membrane coincides with a productive reorientation of SOS at the membrane and increased accessibility of both Ras binding sites on SOS.

  • Organizational Affiliation

    Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Son of sevenless homolog 11,049Homo sapiensMutation(s): 0 
Gene Names: SOS1
UniProt & NIH Common Fund Data Resources
Find proteins for Q07889 (Homo sapiens)
Explore Q07889 
Go to UniProtKB:  Q07889
PHAROS:  Q07889
GTEx:  ENSG00000115904 
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ07889
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 3.18 Å
  • R-Value Free: 0.312 
  • R-Value Work: 0.259 
  • R-Value Observed: 0.264 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 150.961α = 90
b = 160.918β = 90
c = 118.868γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
PDB_EXTRACTdata extraction

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2010-02-16
    Type: Initial release
  • Version 1.1: 2011-07-13
    Changes: Version format compliance
  • Version 1.2: 2017-11-01
    Changes: Advisory, Refinement description
  • Version 1.3: 2024-02-21
    Changes: Advisory, Data collection, Database references