期刊
BIOCHEMICAL JOURNAL
卷 429, 期 -, 页码 63-72出版社
PORTLAND PRESS LTD
DOI: 10.1042/BJ20091953
关键词
arginylated calreticulin; calcium; post-translational modification; retrotranslocation; stress granule
资金
- Agencia Nacional de Promocion Cientifica y Technologica [BID 1728/OC-AR PICT, 1661]
- Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET)
- SECyT Universidad Nacional de Cordoba
Post-translational modifications of proteins are important for the regulation of cell functions; one of these modifications is post-translational arginylation. In the present study, we show that cytoplasmic CRT (calreticulin) is arginylated by ATE I (arginyl-tRNA protein transferase). We also show that a pool of CRT undergoes retrotranslocation from the ER (endoplasmic reticulum) to the cytosol, because in CRT-knockout cells transfected with full-length CRT (that has the signal peptide), cytoplasmic CRT appears as a consequence of its expression and processing in the ER. After the cleavage of the signal peptide, an N-terminal arginylatable residue is revealed prior to retrotranslocation to the cytoplasm where arginylation takes place. SGs (stress granules) from ATE1-knockout cells do not contain CRT, indicating that CRT arginylation is required for its association to SGs. Furthermore, R-CRT (arginylated CRT) in the cytoplasm associates with SGs in cells treated with several stressors that lead to a reduction of intracellular Ca2+ levels. However, in the presence of stressors that do not affect Ca2+ levels, R-CRT is not recruited to these loci despite the fact that SGs are formed, demonstrating Ca2+-dependent R-CRT association to SGs. We conclude that post-translational arginylation of retrotranslocated CRT, together with the decrease in intracellular Ca2+, promotes the association of CRT to SGs.
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