AI Article Synopsis
- ERj1p is a membrane protein in the endoplasmic reticulum that interacts with ribosomes and the chaperone BiP, impacting protein synthesis and potentially serving as a transcription factor.
- Specific regions within the cytosolic domain of ERj1p are responsible for its various functions, including a charged nonapeptide necessary for ribosome binding at the tunnel exit.
- ERj1p has a dual role in gene regulation: it inhibits translation without BiP present, and another charged oligopeptide enables its interaction with importin beta for nuclear import and subsequent DNA action.
Article Abstract
ERj1p is a membrane protein of the endoplasmic reticulum (ER) that can recruit the ER lumenal chaperone BiP to translating ribosomes. ERj1p can also modulate protein synthesis at initiation and is predicted to be a membrane-tethered transcription factor. Here we attribute the various functions of ERj1p to distinct regions within its cytosolic domain. A highly positively charged nonapeptide within this domain is necessary and sufficient for binding to ribosomes. Binding of ERj1p to ribosomes involves the 28S ribosomal RNA and occurs at the tunnel exit. Additionally, ERj1p has a dual regulatory role in gene expression: ERj1p inhibits translation in the absence of BiP, and another charged oligopeptide within the cytosolic domain of ERj1p mediates binding of the nuclear import factor importin beta and import into the nucleus, thereby paving the way for subsequent action on genomic DNA.
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ERj1p has a basic role in protein biogenesis at the endoplasmic reticulum.
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Article Synopsis
- ERj1p is a membrane protein in the endoplasmic reticulum that interacts with ribosomes and the chaperone BiP, impacting protein synthesis and potentially serving as a transcription factor.
- Specific regions within the cytosolic domain of ERj1p are responsible for its various functions, including a charged nonapeptide necessary for ribosome binding at the tunnel exit.
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ERj1p uses a universal ribosomal adaptor site to coordinate the 80S ribosome at the membrane.
Nat Struct Mol Biol
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Institut für Biochemie der Charité, University Medical School Berlin, Monbijoustr. 2, 10117 Berlin, Germany.
Ribosomes translating secretory and membrane proteins are targeted to the endoplasmic reticulum membrane and attach to the protein-conducting channel and ribosome-associated membrane proteins (RAMPs). Recently, a new RAMP, ERj1p, has been identified that recruits BiP to ribosomes and regulates translational activity. Here we present the cryo-EM structure of a ribosome-ERj1p complex, revealing how ERj1p coordinates the ribosome at the membrane and how allosteric effects may mediate ERj1p's regulatory activity.
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