Journal article
Divergent regulation of protein synthesis in the cytosol and endoplasmic reticulum compartments of mammalian cells
Molecular biology of the cell, Vol.19(2), pp.623-632
02/01/2008
DOI: 10.1091/mbc.E07-07-0677
PMCID: PMC2230589
PMID: 18077556
Abstract
In eukaryotic cells, mRNAs encoding signal sequence-bearing proteins undergo translation-dependent trafficking to the endoplasmic reticulum (ER), thereby restricting secretory and integral membrane protein synthesis to the ER compartment. However, recent studies demonstrating that mRNAs encoding cytosolic/nucleoplasmic proteins are represented on ER-bound polyribosomes suggest a global role for the ER in cellular protein synthesis. Here, we examined the steady-state protein synthesis rates and compartmental distribution of newly synthesized proteins in the cytosol and ER compartments. We report that ER protein synthesis rates exceed cytosolic protein synthesis rates by 2.5-to 4-fold; yet, completed proteins accumulate to similar levels in the two compartments. These data suggest that a significant fraction of cytosolic proteins undergo synthesis on ER-bound ribosomes. The compartmental differences in steady-state protein synthesis rates correlated with a divergent regulation of the tRNA aminoacylation/deacylation cycle. In the cytosol, two pathways were observed to compete for aminoacyl-tRNAs-protein synthesis and aminoacyl-tRNA hydrolysis-whereas on the ER tRNA deacylation is tightly coupled to protein synthesis. These findings identify a role for the ER in global protein synthesis, and they suggest models where compartmentalization of the tRNA acylation/deacylation cycle contributes to the regulation of global protein synthesis rates.
Details
- Title: Subtitle
- Divergent regulation of protein synthesis in the cytosol and endoplasmic reticulum compartments of mammalian cells
- Creators
- Samuel B. Stephens - Duke UniversityChristopher V. Nicchitta - Duke University
- Resource Type
- Journal article
- Publication Details
- Molecular biology of the cell, Vol.19(2), pp.623-632
- Publisher
- Amer Soc Cell Biology
- DOI
- 10.1091/mbc.E07-07-0677
- PMID
- 18077556
- PMCID
- PMC2230589
- ISSN
- 1059-1524
- eISSN
- 1939-4586
- Number of pages
- 10
- Grant note
- GM-077382 / National Institutes of Health; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA 0515333U / American Heart Association R01GM077382 / NATIONAL INSTITUTE OF GENERAL MEDICAL SCIENCES; United States Department of Health & Human Services; National Institutes of Health (NIH) - USA; NIH National Institute of General Medical Sciences (NIGMS)
- Language
- English
- Date published
- 02/01/2008
- Academic Unit
- Fraternal Order of Eagles Diabetes Research Center; Endocrinology and Metabolism; Internal Medicine
- Record Identifier
- 9984359888002771
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