Regulation of copper-dependent endocytosis and vacuolar degradation of the yeast copper transporter, Ctr1p, by the Rsp5 ubiquitin ligase

Traffic. 2007 Oct;8(10):1375-84. doi: 10.1111/j.1600-0854.2007.00616.x. Epub 2007 Jul 20.


The Saccharomyces cerevisiae high-affinity copper transporter, Ctr1p, mediates cellular uptake of Cu(I). We report that when copper (50 microm CuSO(4)) is added to the growth medium of copper-starved cells, Ctr1p is rapidly internalized by endocytosis, delivered to the lumen of the lysosome-like vacuole and slowly degraded by vacuolar proteases. Through analysis of the trafficking and degradation of Ctr1p mutants, two lysine residues in the C-terminal cytoplasmic tail of Ctr1p, Lys340 and Lys345, were found to be critical for copper-dependent endocytosis and degradation. In response to copper addition, Ctr1p was found to be ubiquitylated and a mutation in the Rsp5 ubiquitin ligase largely abolished ubiquitylation, endocytosis and degradation. In a strain lacking the Rsp5p accessory factors Bul1p and Bul2p, endocytosis and degradation of Ctr1p-green fluorescent protein were substantially diminished. Surprisingly, a Ctr1p mutant that lacks Lys340 and Lys345 was still ubiquitylated in a copper-dependent manner, indicating that ubiquitylation of Ctr1p on other sites is insufficient to drive copper-dependent endocytosis and degradation. This study demonstrates that copper regulates turnover of Ctr1p by stimulating Rsp5p-dependent endocytosis and degradation of Ctr1p in the vacuole.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Cation Transport Proteins / metabolism*
  • Copper / physiology*
  • Copper Transporter 1
  • Endocytosis / physiology*
  • Endosomal Sorting Complexes Required for Transport
  • Protein Transport / physiology
  • Saccharomyces cerevisiae / enzymology*
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Saccharomyces cerevisiae Proteins / physiology*
  • Ubiquitin-Protein Ligase Complexes / physiology*
  • Vacuoles / enzymology
  • Vacuoles / metabolism*


  • CTR1 protein, S cerevisiae
  • Cation Transport Proteins
  • Copper Transporter 1
  • Endosomal Sorting Complexes Required for Transport
  • Saccharomyces cerevisiae Proteins
  • Copper
  • Ubiquitin-Protein Ligase Complexes
  • RSP5 protein, S cerevisiae