title: Two nuclear mutations that block mitochondrial protein import in yeast.
abstract: We isolated two yeast mutants that are temperature-sensitive for import of mitochondrial proteins. Each strain contains a single mutation that results in arrest of growth and accumulation of precursor to the beta subunit of the mitochondrial F1-ATPase after incubation at 37 degrees C. These lesions (mas1 and mas2) are nonallelic and recessive. Cells harboring either mutation stop growing only after 2-3 generations at 37 degrees C. Import of the F1 beta subunit at 37 degrees C is more than 250 times slower in mas1 and 15 times slower in mas2 than in wild-type cells. At 23 degrees C, import occurs with similar rates in mutant and wild-type cells. The two mutations also reduce the rate of import of other proteins; however, import of different precursors is affected to different degrees in the two strains. The temperature-sensitive step in import in both mas1 and mas2 occurs before arrival of precursors in the mitochondrial matrix.
mesh_terms: D001692:Biological Transport; D002467:Cell Nucleus / Q000502:physiology; D003580:Cytochromes / Q000378:metabolism; D046911:Macromolecular Substances; D008928:Mitochondria / Q000502:physiology*; D009154:Mutation; D006180:Proton-Translocating ATPases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*
chemical_list: D003580:Cytochromes; D046911:Macromolecular Substances; D006180:Proton-Translocating ATPases