Heat shock-induced translational alterations in HeLa cells. Initiation factor modifications and the inhibition of translation.
Heat shock at 45 degrees C virtually abolishes protein synthesis in HeLa cells, but return to 37 degrees C effects a complete recovery and the concomitant synthesis of heat shock-induced proteins. Heat shock induces polysome disaggregation, indicating initiation is principally inhibited. In vitro assays for initiation factor activities reveal heat shock inhibits eukaryotic initiation factor 2 (eIF-2), eIF-(3 + 4F), and eIF-4B. Immunoblot analyses show that eIF-2 alpha and eIF-2 beta become modified during heat shock, and eIF-4B variants disappear. Upon return to 37 degrees C, these alterations reverse. The modifications of eIF-2 alpha and eIF-4B are due to phosphorylation and dephosphorylation, respectively. Enzymatic activities induced by heat shock inhibit protein synthesis and modify initiation factors in a rabbit reticulocyte lysate. Initiation factor modifications may contribute to, or cause, protein synthesis inhibition.
D002499:Centrifugation, Density Gradient; D004591:Electrophoresis, Polyacrylamide Gel; D006367:HeLa Cells / Q000032:analysis*; D006360:Heat-Shock Proteins / Q000096:biosynthesis; D006358:Hot Temperature; D006801:Humans; D007163:Immunosorbent Techniques; D010448:Peptide Initiation Factors / Q000096:biosynthesis; D014176:Protein Biosynthesis
D006360:Heat-Shock Proteins; D010448:Peptide Initiation Factors