Heat shock causes diverse changes in the phosphorylation of the ribosomal proteins of mammalian cells

Abstract

When HeLa cells or BHK cells were subjected to heat shock at 42°C (for 2 h) or 45°C (for 10 min) there was extensive dephosphorylation of ribosomal protein S6. Concomitantly ribosomal protein L14, which is not significantly phosphorylated in normal cells, became phosphorylated, as did a non-structural protein of M _r = 27 000, associated with the ribosomes. The latter effects were not prevented by cycloheximide or actinomycin D. When cells shocked at 45°C for 10 min were returned to 37°C for 2 h there was rephosphorylation of ribosomal protein S6 and dephosphorylation of the 27 kDa protein, but not of ribosomal protein L14.