Phosphorylation-dephosphorylation changes in yeast ribosomal proteins S2 and S6 during growth under normal and hyperthermal conditions.

Dynamic changes were observed in the phosphorylation level of a basic ribosomal protein S6 under different growth conditions of yeast culture. The maximum level of S6 phosphorylation occurred within 30 min of 32P-labelling after the transfer of cells into fresh nutrient medium. The elevation of temperature to supraoptimal level (38 degrees C and 41 degrees C) led to extensive dephosphorylation of S6 protein, and the recovery from heat shock was characterized by its rephosphorylation. Contrary to S6, phosphorylation of ribosomal protein S2 remained on unchanged level, irrespective of growth conditions.