ERj1p has a basic role in protein biogenesis at the endoplasmic reticulum.
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.
Dudek
Johanna
J
Medizinische Biochemie und Molekularbiologie, Universität des Saarlandes, D-66421 Homburg, Germany.
Greiner
Markus
M
Müller
Anika
A
Hendershot
Linda M
LM
Kopsch
Katharina
K
Nastainczyk
Wolfgang
W
Zimmermann
Richard
R
D000818:Animals; D004721:Endoplasmic Reticulum / Q000378:metabolism*; D000091342:Endoplasmic Reticulum Chaperone BiP; D005786:Gene Expression Regulation / Q000235:genetics*; D050956:HSP40 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D006360:Heat-Shock Proteins / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008954:Models, Biological; D018832:Molecular Chaperones / Q000378:metabolism; D009363:Neoplasm Proteins / Q000235:genetics / Q000378:metabolism*; D014176:Protein Biosynthesis / Q000235:genetics*; D017434:Protein Structure, Tertiary; D012339:RNA, Ribosomal, 28S / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D013329:Structure-Activity Relationship; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism*; D028961:beta Karyopherins / Q000378:metabolism
C092319:Dnajc1 protein, mouse; D000091342:Endoplasmic Reticulum Chaperone BiP; D050956:HSP40 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D009363:Neoplasm Proteins; D012339:RNA, Ribosomal, 28S; D014157:Transcription Factors; D028961:beta Karyopherins