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L25 functions as a conserved ribosomal docking site shared by nascent chain‐associated complex and signal‐recognition particle
Author(s) -
Grallath Silke,
Schwarz Juliane P,
Böttcher Ulrike M K,
Bracher Andreas,
Hartl F Ulrich,
Siegers Katja
Publication year - 2006
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.1038/sj.embor.7400551
Subject(s) - signal recognition particle , ribosome , protein subunit , ribosomal protein , protein targeting , endoplasmic reticulum , chaperone (clinical) , microbiology and biotechnology , ribosomal rna , biology , eukaryotic large ribosomal subunit , biochemistry , rna , gene , membrane protein , medicine , pathology , membrane
The nascent chain‐associated complex (NAC) is a dimeric protein complex of archaea and eukarya that interacts with ribosomes and translating polypeptide chains. We show that, in yeast, NAC and the signal‐recognition particle (SRP) share the universally conserved ribosomal protein L25 as a docking site, which is in close proximity to the ribosomal exit tunnel. The amino‐terminal segment of β‐NAC was found to be required for L25 binding. Purified NAC can prevent protein aggregation in vitro and thus shows certain properties of a molecular chaperone. Interestingly, the α‐subunit of NAC interacts with the 54 kDa subunit of SRP. Consistent with a regulatory role of NAC in protein translocation into the endoplasmic reticulum (ER), we find that deletion of NAC results in an induction of the ER stress‐response pathway. These results identify L25 as a conserved interaction platform for specific cytosolic factors that guide nascent polypeptides to their proper cellular destination.