Regulated release of L13a from the 60S ribosomal subunit as a mechanism of transcript-specific translational control.
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Mazumder B, Sampath P, Seshadri V, Maitra RK, DiCorleto PE, Fox PL
Regulated release of L13a from the 60S ribosomal subunit as a mechanism of transcript-specific translational control.
Cell. 2003 Oct 17;115(2):187-98.
- PubMed ID
- 14567916 [ View in PubMed]
- Abstract
Transcript-specific translational control is generally directed by binding of trans-acting proteins to structural elements in the untranslated region (UTR) of the target mRNA. Here, we elucidate a translational silencing mechanism involving regulated release of an integral ribosomal protein and subsequent binding to its target mRNA. Human ribosomal protein L13a was identified as a candidate interferon-Gamma-Activated Inhibitor of Translation (GAIT) of ceruloplasmin (Cp) mRNA by a genetic screen for Cp 3'-UTR binding proteins. In vitro activity of L13a was shown by inhibition of target mRNA translation by recombinant protein. In response to interferon-gamma in vivo, the entire cellular pool of L13a was phosphorylated and released from the 60S ribosomal subunit. Released L13a specifically bound the 3'-UTR GAIT element of Cp mRNA and silenced translation. We propose a model in which the ribosome functions not only as a protein synthesis machine, but also as a depot for regulatory proteins that modulate translation.