A stimulatory role for the La-related protein 4B in translation.
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Schaffler K, Schulz K, Hirmer A, Wiesner J, Grimm M, Sickmann A, Fischer U
A stimulatory role for the La-related protein 4B in translation.
RNA. 2010 Aug;16(8):1488-99. doi: 10.1261/rna.2146910. Epub 2010 Jun 23.
- PubMed ID
- 20573744 [ View in PubMed]
- Abstract
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.