Signal-sequence recognition by an Escherichia coli ribonucleoprotein complex.

J Luirink; S High; H Wood; A Giner; D Tollervey; B Dobberstein

doi:10.1038/359741a0

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Signal-sequence recognition by an Escherichia coli ribonucleoprotein complex.

J Luirink·S High·H Wood·A Giner·D Tollervey·B Dobberstein

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Abstract

Hydrophobic signal-sequences direct the transfer of secretory proteins across the inner membrane of prokaryotes and the endoplasmic reticulum membranes of eukaryotes. In mammalian cells, signal-sequences are recognized by the 54K protein (M(r) 54,000) of the signal recognition particle (SRP) which is believed to hold the nascent chain in a translocation-competent conformation until it contacts the endoplasmic reticulum membrane. The SRP consists of a 7S RNA and six different polypeptides. The 7S RNA and the 54K signal-sequence-binding protein (SRP54) of mammalian SRP exhibit strong sequence similarity to the 4.5S RNA and P48 protein (Ffh) of Escherichia coli which form a ribonucleoprotein particle. Depletion of 4.5S RNA or overproduction of P48 causes the accumulation of the beta-lactamase precursor, although not of other secretory proteins. Whether 4.5S RNA and P48 are part of an SRP-like complex with a role in protein export is controversial. Here we show that the P48/4.5S RNA ribonucleoprotein complex interacts specifically with the signal sequence of a nascent secretory protein and therefore is a signal recognition particle.

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Bacterial Proteins Biological Transport Cross-Linking Reagents Escherichia coli Macromolecular Substances Protein Precursors Protein Sorting Signals RNA, Bacterial Ribonucleoproteins Signal Recognition Particle Journal Article

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J Luirink, S High, H Wood, A Giner, D Tollervey, B Dobberstein. 1992-10-22. Signal-sequence recognition by an Escherichia coli ribonucleoprotein complex.. https://doi.org/10.1038/359741a0

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