Patterns of protein synthesis in various cells after extreme heat shock

Abstract

The analysis of proteins synthesized in rat thymocytes and mouse teratocarcinoma PCC-4 Azal and myeloma Sp2/0 cells after 1 h of treatment at 42 or 44 °C was carried out. Shock at 42 °C reduced the total synthetic rate of proteins in all three cell lines and induced “classical” heat-shock protein with a mass of 70 kDa (hsp70). Heat shock at 44 °C resulted in almost complete inhibition of protein synthesis; only a small amount of hsp70 was synthesized. Meanwhile a new 48-kDa polypeptide (pI = 7.5) was found in the cells exposed to severe heat shock. This protein was compared by peptide mapping with other known polypeptides of the same size: heat-shock protein from chicken embryo cells and mitogen-stimulated polypeptide from human lymphoid cells. The peptide maps were not identical. It was also shown that after a shock at 44 °C teratocarcinoma cells were able to accumulate anomalous amounts of hsp70 despite hsp70 synthesis inhibition. The data show that reaction of various cells to extreme heat shock depends heavily on cell type.