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ERj1p has a basic role in protein biogenesis at the endoplasmic reticulum
Johanna Dudek1, Markus Greiner, Anika Müller
1Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, D-66421 Homburg, Germany.
Nature Structural & Molecular Biology
|October 26, 2005
Summary
ERj1p, an endoplasmic reticulum protein, binds ribosomes via a charged peptide, modulating protein synthesis. It also targets the nucleus to regulate gene expression, acting as a transcription factor.
Area of Science:
- Cell Biology
- Molecular Biology
- Protein Synthesis Regulation
Background:
- ERj1p is an endoplasmic reticulum (ER) membrane protein with known roles in recruiting BiP chaperone to ribosomes.
- ERj1p is also implicated in modulating protein synthesis initiation and predicted to function as a membrane-tethered transcription factor.
Purpose of the Study:
- To delineate the distinct functional regions within the cytosolic domain of ERj1p.
- To elucidate the molecular mechanisms underlying ERj1p's diverse roles in protein synthesis and gene expression.
Main Methods:
- Analysis of ERj1p's cytosolic domain to identify functional regions.
- Investigation of ERj1p's interaction with ribosomes, including specific rRNA components and binding sites.
- Characterization of ERj1p's role in translation inhibition and nuclear import.
Main Results:
- A positively charged nonapeptide in ERj1p's cytosolic domain is essential and sufficient for ribosome binding at the 28S ribosomal RNA tunnel exit.
- ERj1p inhibits translation in the absence of BiP.
- Another charged oligopeptide mediates importin beta binding and nuclear import of ERj1p.
Conclusions:
- ERj1p possesses distinct functional domains within its cytosolic region, mediating ribosome interaction and nuclear translocation.
- ERj1p acts as a dual regulator of gene expression, inhibiting translation and facilitating nuclear import for genomic DNA interaction.