2ged
From Proteopedia
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Signal Recognition Particle Receptor Beta-Subunit in nucleotide-free dimerized form
Overview
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 Structure
2GED is a Single protein structure of sequence from Saccharomyces cerevisiae with SO4 as ligand. Full crystallographic information is available from OCA.
Reference
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
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