2GED

Signal Recognition Particle Receptor Beta-Subunit in nucleotide-free dimerized form

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.20 Å
  • R-Value Free: 0.239 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.188 

wwPDB Validation   3D Report Full Report


This is version 1.3 of the entry. See complete history. 


Literature

Homodimerization of the G protein SR{beta} in the nucleotide-free state involves proline cis/trans isomerization in the switch II region.

Schwartz, T.U., Schmidt, D., Brohawn, S.G., Blobel, G.

(2006) Proc Natl Acad Sci U S A 103: 6823-6828

  • DOI: 10.1073/pnas.0602083103
  • Primary Citation of Related Structures:  
    2GED

  • PubMed Abstract: 

    • Protein translocation across and insertion into membranes is essential to all life forms. Signal peptide-bearing nascent polypeptide chains emerging from the ribosome are first sampled by the signal-recognition particle (SRP), then targeted to the membrane via the SRP receptor (SR), and, finally, transferred to the protein-conducting channel ...

    Protein translocation across and insertion into membranes is essential to all life forms. Signal peptide-bearing nascent polypeptide chains emerging from the ribosome are first sampled by the signal-recognition particle (SRP), then targeted to the membrane via the SRP receptor (SR), and, finally, transferred to the protein-conducting channel. In eukaryotes, this process is tightly controlled by the concerted action of three G proteins, the 54-kD subunit of SRP and the alpha- and beta-subunits of SR. We have determined the 2.2-A crystal structure of the nucleotide-free SRbeta domain. Unexpectedly, the structure is a homodimer with a highly intertwined interface made up of residues from the switch regions of the G domain. The remodeling of the switch regions does not resemble any of the known G protein switch mechanisms. Biochemical analysis confirms homodimerization in vitro, which is incompatible with SRalpha binding. The switch mechanism involves cis/trans isomerization of a strictly conserved proline, potentially implying a new layer of regulation of cotranslational transport.

    Related Citations: 
    • Circular permutation as a tool to reduce surface entropy triggers crystallization of the signal recognition particle receptor beta subunit.
      Schwartz, T.U., Walczak, R., Blobel, G.
      (2004) Protein Sci 13: 2814
    Organizational Affiliation: 

    Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA. tus@mit.edu



Macromolecules
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(by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChainsSequence LengthOrganismDetailsImage
Signal recognition particle receptor beta subunitA, B193Saccharomyces cerevisiaeMutation(s): 0 
Gene Names: SRP102
UniProt
Find proteins for P36057 (Saccharomyces cerevisiae (strain ATCC 204508 / S288c))
Explore P36057 
Go to UniProtKB:  P36057
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP36057
Protein Feature View
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  • Reference Sequence
Small Molecules
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.20 Å
  • R-Value Free: 0.239 
  • R-Value Work: 0.183 
  • R-Value Observed: 0.188 
  • Space Group: P 61
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 74.996α = 90
b = 74.996β = 90
c = 158.475γ = 120
Software Package:
Software NamePurpose
REFMACrefinement
DENZOdata reduction
SCALEPACKdata scaling
BEASTphasing

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2006-04-18
    Type: Initial release
  • Version 1.1: 2008-05-01
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2017-08-02
    Changes: Source and taxonomy