Open AccessA stimulatory role for the La-related protein 4B in translation
Author(s) -
Katrin Schäffler,
Kristina Schulz,
Anja Hirmer,
Julia Wiesner,
Michael Grimm,
Albert Sickmann,
Utz Fischer
Publication year - 2010
Publication title -
rna
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.037
H-Index - 171
eISSN - 1469-9001
pISSN - 1355-8382
DOI - 10.1261/rna.2146910
Subject(s) - biology , ribosome , polysome , translation (biology) , stress granule , rna binding protein , microbiology and biotechnology , protein subunit , protein biosynthesis , poly(a) binding protein , initiation factor , ribosomal protein , eukaryotic ribosome , rna , messenger rna , biochemistry , gene
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.
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