A stimulatory role for the La-related protein 4B in translation

La-related proteins (LARPs) belong to an evolutionarily conserved family of factors with predicted roles in RNA metabolism. Here, we have analyzed the cellular interactions and function of LARP4B, a thus far uncharacterized member of the LARP family. We show that LARP4B is a cytosolic protein that a...

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Bibliographic Details
Published in:RNA (Cambridge) 2010-08, Vol.16 (8), p.1488-1499
Main Authors: Schäffler, Katrin, Schulz, Kristina, Hirmer, Anja, Wiesner, Julia, Grimm, Michael, Sickmann, Albert, Fischer, Utz
Format: Article
Language:English
Subjects:
Antigens, Nuclear - genetics
Antigens, Nuclear - metabolism
DNA-Binding Proteins - genetics
DNA-Binding Proteins - metabolism
Ku Autoantigen
Polyribosomes - genetics
Polyribosomes - metabolism
Protein Biosynthesis
Ribosome Subunits, Small, Eukaryotic
Ribosomes - genetics
Ribosomes - metabolism
RNA, Messenger - genetics
RNA, Messenger - metabolism
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Summary:La-related proteins (LARPs) belong to an evolutionarily conserved family of factors with predicted roles in RNA metabolism. Here, we have analyzed the cellular interactions and function of LARP4B, a thus far uncharacterized member of the LARP family. We show that LARP4B is a cytosolic protein that accumulates upon arsenite treatment in cellular stress granules. Biochemical experiments further uncovered an interaction of LARP4B with the cytosolic poly(A) binding protein 1 (PABPC1) and the receptor for activated C Kinase (RACK1), a component of the 40S ribosomal subunit. Under physiological conditions, LARP4B co-sedimented with polysomes in cellular extracts, suggesting a role in translation. In agreement with this notion, overexpression of LARP4B stimulated protein synthesis, whereas knockdown of the factor by RNA interference impaired translation of a large number of cellular mRNAs. In sum, we identified LARP4B as a stimulatory factor of translation. We speculate that LARP4B exerts its function by bridging mRNA factors of the 3' end with initiating ribosomes.
ISSN:1355-8382
1469-9001
DOI:10.1261/rna.2146910