Stressful initiations.
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.
Anderson
Paul
P
Division of Rheumatology, Immunology and Allergy, Brigham and Women's Hospital, Smith 652, One Jimmy Fund Way, Boston, MA 02115, USA. panderson@rics.bwh.harvard.edu
Kedersha
Nancy
N
D001481:Basal Metabolism / Q000502:physiology*; D002460:Cell Line; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D006160:Guanosine Triphosphate / Q000378:metabolism; D002479:Inclusion Bodies / Q000378:metabolism*; D046911:Macromolecular Substances; D008957:Models, Genetic; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000378:metabolism; D012358:RNA, Transfer, Met / Q000378:metabolism
D015852:Eukaryotic Initiation Factor-2; D046911:Macromolecular Substances; D012333:RNA, Messenger; D012358:RNA, Transfer, Met; D006160:Guanosine Triphosphate