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Using SecM Arrest Sequence as a Tool to Isolate Ribosome Bound Polypeptides
Published on: June 19, 2012
Association of Escherichia coli ribosomes with the inner membrane requires the signal recognition particle receptor
1Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel.
Abstract:
In mammalian cells, as well as Escherichia coli, ribosomes translating membrane proteins interact cotranslationally with translocons in the membrane, and this interaction is essential for proper insertion of nascent polypeptides into the membrane. Both the signal recognition particle (SRP) and its receptor (SR) are required for functional association of ribosomes translating integral membrane proteins with the translocon. Herein, we confirm that membrane targeting of E. coli ribosomes requires the prokaryotic SRalpha homolog FtsY in vivo. Surprisingly, however, depletion of the E. coli SRP54 homolog (Ffh) has no significant effect on binding of ribosomes to the membrane, although Ffh depletion is detrimental to growth. These and other observations suggest that, in E. coli, SRP may operate downstream of SR-mediated targeting of ribosomes to the plasma membrane.
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