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.
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
Paul
P
Anderson
Nancy
N
Kedersha
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