An N-end rule destabilization mutant reveals pre-Golgi requirements for Sec7p in yeast membrane traffic

Biochem Biophys Res Commun. 1998 Feb 4;243(1):191-8. doi: 10.1006/bbrc.1998.8084.

Abstract

Sec7 protein (Sec7p) is required for membrane traffic in the yeast secretory pathway. Because Sec7p regulates more than one stage in the pathway, it has been difficult to assign the most proximal requirement for Sec7p action. We have engineered a novel mutant whose Sec7p levels are regulated by growth conditions and by selective protein destabilization according to the N-end rule. Sec7p depletion causes cell growth arrest and accumulation of transport proteins with post-translational modifications indicative of Sec7p dependence for ER-to-Golgi traffic, in addition to the already characterized Golgi requirements. Immuno-EM of sec7 revealed exaggeration of ER and Golgi membranes with protein accumulation in these exaggerated structures, suggesting that these regions may represent staging areas for cargo sorting and vesicle assembly.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biological Transport, Active
  • Carboxypeptidases / metabolism
  • Cathepsin A
  • Cell Division
  • Endoplasmic Reticulum / metabolism
  • Endoplasmic Reticulum / ultrastructure
  • Fungal Proteins / genetics*
  • Fungal Proteins / metabolism*
  • Genes, Fungal
  • Genetic Engineering
  • Golgi Apparatus / metabolism
  • Golgi Apparatus / ultrastructure
  • Guanine Nucleotide Exchange Factors*
  • Intracellular Membranes / metabolism
  • Intracellular Membranes / ultrastructure
  • Membrane Glycoproteins / metabolism
  • Microscopy, Immunoelectron
  • Mutation*
  • Saccharomyces cerevisiae / genetics*
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae / ultrastructure
  • Saccharomyces cerevisiae Proteins*

Substances

  • Fungal Proteins
  • GAS1 protein, S cerevisiae
  • Guanine Nucleotide Exchange Factors
  • Membrane Glycoproteins
  • Saccharomyces cerevisiae Proteins
  • Sec7 guanine nucleotide exchange factors
  • Carboxypeptidases
  • Cathepsin A