Differential synthesis of glyceraldehyde-3-phosphate dehydrogenase polypeptides in stressed yeast cells.

Three unlinked genes, TDH1, TDH2 and TDH3, encode the glycolytic enzyme glyceraldehyde-3-phosphate dehydrogenase (triose-phosphate dehydrogenase; TDH) in the yeast Saccharomyces cerevisiae. We demonstrate that the synthesis of the three encoded TDH polypeptides (TDHa, TDHb and TDHc, respectively) is not co-ordinately regulated and that TDHa is only synthesised as cells enter stationary phase, due to glucose starvation, or in heat-shocked cells. Furthermore, the synthesis of TDHb, but not TDHc, is strongly repressed by a heat shock. Hence, the TDHa enzyme may play a cellular role, distinct from glycolysis, that is required by stressed cells.