Catabolite inactivation of the yeast maltose transporter requires ubiquitin-ligase npi1/rsp5 and ubiquitin-hydrolase npi2/doa4

FEMS Microbiol Lett. 1997 Feb 15;147(2):273-7. doi: 10.1111/j.1574-6968.1997.tb10253.x.


The maltose transporter in Saccharomyces cerevisiae is degraded in the vacuole after internalization by endocytosis when protein synthesis is impaired and a fermentable substrate is present. The possible implication of the ubiquitin pathway in this inactivation, known as catabolite inactivation, has been investigated. Using mutants deficient in npi1/rsp5 ubiquitin-protein ligase and npi2/doa4 ubiquitin-protein hydrolase, we have shown that these two enzymes are required for normal endocytosis and degradation of the transporter. These facts indicate that the ubiquitin pathway is involved in catabolite inactivation of the maltose transporter. The results also revealed that both enzymes act in the internalization step of endocytosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Carrier Proteins / immunology
  • Carrier Proteins / metabolism*
  • Electrophoresis, Polyacrylamide Gel
  • Endocytosis / genetics
  • Endopeptidases*
  • Endosomal Sorting Complexes Required for Transport
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism*
  • Gene Expression Regulation, Enzymologic
  • Gene Expression Regulation, Fungal
  • Immunoblotting
  • Ligases / genetics*
  • Ligases / metabolism*
  • Luminescent Measurements
  • Maltose / metabolism*
  • Plasmids
  • Recombination, Genetic
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins*
  • Transformation, Genetic
  • Ubiquitin Thiolesterase
  • Ubiquitin-Protein Ligase Complexes*
  • Ubiquitin-Protein Ligases


  • Carrier Proteins
  • DOA4 protein, S cerevisiae
  • Endosomal Sorting Complexes Required for Transport
  • Fungal Proteins
  • Saccharomyces cerevisiae Proteins
  • Maltose
  • Ubiquitin-Protein Ligase Complexes
  • Ubiquitin-Protein Ligases
  • Endopeptidases
  • Ubiquitin Thiolesterase
  • Ligases
  • RSP5 protein, S cerevisiae