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Science Signaling  06 Jan 2009:
Vol. 2, Issue 52, pp. ec7
DOI: 10.1126/scisignal.252ec7

Cotranslational protein targeting to membranes involves the signal recognition particle (SRP) and its receptor. SRP contains a noncoding RNA, which catalytically accelerates the interaction of SRP with its receptor. Bradshaw et al. now show that SRP RNA is a molecular switch that is triggered by signal sequences on secretory and membrane proteins. When activated in response to signal sequence binding, SRP RNA profoundly accelerates the forward rate of SRP binding to the SRP receptor. Previously, this effect was masked because detergent mimics the signal peptide, activating SRP RNA constitutively. Thus, cargo (the signal sequence) controls the SRP protein targeting machine.

N. Bradshaw, S. B. Neher, D. S. Booth, P. Walter, Signal sequences activate the catalytic switch of SRP RNA. Science 323, 127–130 (2009). [Abstract] [Full Text]

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