2ged: Difference between revisions

Revision as of 05:00, 4 May 2008

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

OverviewOverview

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.

About this StructureAbout this Structure

2GED is a Single protein structure of sequence from Saccharomyces cerevisiae. Full crystallographic information is available from OCA.

ReferenceReference

Homodimerization of the G protein SRbeta in the nucleotide-free state involves proline cis/trans isomerization in the switch II region., Schwartz TU, Schmidt D, Brohawn SG, Blobel G, Proc Natl Acad Sci U S A. 2006 May 2;103(18):6823-8. Epub 2006 Apr 20. PMID:16627619 Page seeded by OCA on Sun May 4 05:00:37 2008

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OCA

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 '''Signal Recognition Particle Receptor Beta-Subunit in nucleotide-free dimerized form'''
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 [[Category: Schmidt, D.]]
 [[Category: Schwartz, T U.]]
-[[Category: circular permutation]]
+[[Category: Circular permutation]]
-[[Category: g protein]]
+[[Category: G protein]]
-[[Category: proline isomerization]]
+[[Category: Proline isomerization]]
-[[Category: protein transport]]
+[[Category: Protein transport]]
-[[Category: signal recognition particle]]
+[[Category: Signal recognition particle]]
+''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sun May  4 05:00:37 2008''
-''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Mar 31 03:15:38 2008''