Study of a temperature-sensitive mutant of the ras-related YPT1 gene product in yeast suggests a role in the regulation of intracellular calcium

Cell. 1988 May 20;53(4):635-47. doi: 10.1016/0092-8674(88)90579-x.


Intragenic mutations were isolated that suppressed the dominant-lethal phenotype of the YPT1ile121 mutant gene in a temperature-dependent fashion. Among different amino acid substitutions resulting from single point mutations, two, Ala161----Val (A161V) and Met165----Ile (M165I), restored the function of the YPT1ile121 mutant protein. Mutants expressing the YPT1ile121/val161 allele (ypt1ts) only, grew normally at temperatures up to 30 degrees C but were arrested at 37 degrees C. At the restrictive temperature, ypt1ts mutants accumulated ER membranes, small vesicles, and unprocessed invertase, and they exhibited cytoskeletal defects and an enhanced 45Ca2+ uptake. Similar alterations were seen in YPT1-depleted cells. The ypt1ts mutant cells could be rescued from growth arrest by increasing extracellular Ca2+, and, even at the permissive temperature, they displayed increased trifluoperazine sensitivity.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Amino Acid Sequence
  • Calcium / metabolism*
  • Fungal Proteins / genetics*
  • Gene Expression Regulation
  • Genes, Fungal
  • Genes, ras*
  • Microscopy, Electron
  • Molecular Sequence Data
  • Mutation
  • Phenotype
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / growth & development
  • Saccharomyces cerevisiae / metabolism
  • Saccharomyces cerevisiae / ultrastructure
  • Suppression, Genetic
  • Temperature
  • ras Proteins*


  • Fungal Proteins
  • ras Proteins
  • Calcium