Secretion and cell-surface growth are blocked in a temperature-sensitive mutant of Saccharomyces cerevisiae.
Saccharomyces cerevisiae cells contain a small internal pool of the secretory enzymes invertase and acid phosphatase. This pool increases up to 8-fold at 37 degrees C in a temperature-sensitive, secretion-defective mutant strain (sec 1-1). Cell division and incorporation of a sulfate permease activity stop abruptly at the restrictive temperature, while protein synthesis continues for several hours. Electron microscopy of mutant cells incubated at 37 degrees C reveals a large increase in the number of intracellular membrane-bound vesicles, which are shown by histochemical staining to contain the accumulated acid phosphatase. The vesicles are removed and the accumulated enzymes are secreted when cells are returned to a permissive temperature in the presence or absence of cycloheximide. These results are consistent with a vesicle intermediate in the yeast secretory pathway and suggest that exocytosis may contribute to cell-surface growth.
D000135:Acid Phosphatase / Q000378:metabolism*; D002462:Cell Membrane / Q000502:physiology* / Q000648:ultrastructure; D026901:Membrane Transport Proteins / Q000378:metabolism; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000254:growth & development*; D013045:Species Specificity; D013104:Spheroplasts / Q000201:enzymology / Q000648:ultrastructure; D013393:Sucrase / Q000378:metabolism*; D013696:Temperature
D026901:Membrane Transport Proteins; D000135:Acid Phosphatase; D013393:Sucrase