Stressful initiations - PubMed (original) (raw)

. 2002 Aug 15;115(Pt 16):3227-34.

doi: 10.1242/jcs.115.16.3227.

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Stressful initiations

Paul Anderson et al. J Cell Sci. 2002.

Abstract

Stress granules (SGs) are phase-dense particles that appear in the cytoplasm of eukaryotic cells that have been exposed to environmental stress (e.g. heat, oxidative conditions, hyperosmolarity and UV irradiation). SG assembly is a consequence of abortive translational initiation: SGs appear when translation is initiated in the absence of eIF2-GTP-tRNA(i)(Met), the ternary complex that normally loads tRNA(i)(Met) onto the small ribosomal subunit. Stress-induced depletion of eIF2-GTP-tRNA(i)(Met) allows the related RNA-binding proteins TIA-1 and TIAR to promote the assembly of eIF2-eIF5-deficient preinitiation complexes, the core constituents of SGs. The mRNP components that make up the SG are in a dynamic equilibrium with polysomes. As such, the SG appears to constitute a metabolic domain through which mRNPs are continually routed and subjected to triage - they are first monitored for integrity and composition, and then sorted for productive translational initiation or targeted degradation.

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