Ypt32p regulates the translocation of Chs3p from an internal pool to the plasma membrane

Eur J Cell Biol. 2006 Feb;85(2):107-16. doi: 10.1016/j.ejcb.2005.10.006. Epub 2005 Nov 21.


The transport of the chitin synthase III, Chs3p, to the plasma membrane is temporally and spatially regulated. Chs3p is delivered to the plasma membrane at the beginning of the cell cycle, forming chitin rings, and at the end of the cell cycle, forming the primary septum. During the rest of the cell cycle, it is maintained in intracellular compartments, termed chitosomes that share characteristics with the late Golgi and the early endosomes. Chs5p and Chs6p are required for the cell cycle-dependent delivery of Chs3p to the cell surface, but the mechanisms underlying the temporal regulation are still unknown. The Rab proteins, Ypt31/32p, are required for exit of secretory vesicles from the late Golgi and for recycling of proteins between the late Golgi and early endosomes. Either gain of Ypt32p function, by overexpression, or loss-of-function mutations alter the localization of Chs3p-GFP. Moreover, cells overexpressing Ypt32p accumulate chitin at the cell surface independent of Chs5p. Overexpression of Ypt32p also disrupts the localization of the late Golgi protein Sec7. We propose that Ypt31/32p have a role in regulating the delivery of Chs3p to the plasma membrane and deposition of chitin at the cell surface.

MeSH terms

  • Cell Cycle / physiology
  • Cell Membrane / metabolism*
  • Chitin / genetics
  • Chitin / metabolism*
  • Chitin Synthase / physiology
  • Endosomes / chemistry
  • Endosomes / metabolism
  • Gene Expression Regulation, Fungal
  • Golgi Apparatus / chemistry
  • Golgi Apparatus / metabolism
  • Guanine Nucleotide Exchange Factors / analysis
  • Guanine Nucleotide Exchange Factors / metabolism
  • Mutation
  • Protein Transport
  • Pyridinium Compounds / analysis
  • Pyridinium Compounds / metabolism
  • Quaternary Ammonium Compounds / analysis
  • Quaternary Ammonium Compounds / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae Proteins / physiology
  • rab GTP-Binding Proteins / genetics
  • rab GTP-Binding Proteins / metabolism*


  • FM 4-64
  • Guanine Nucleotide Exchange Factors
  • Pyridinium Compounds
  • Quaternary Ammonium Compounds
  • Saccharomyces cerevisiae Proteins
  • Sec7 guanine nucleotide exchange factors
  • Chitin
  • CHS3 protein, S cerevisiae
  • CHS5 protein, S cerevisiae
  • Chitin Synthase
  • YPT31 protein, S cerevisiae
  • YPT32 protein, S cerevisiae
  • rab GTP-Binding Proteins