Binding of plasma membrane lipids recruits the yeast integral membrane protein Ist2 to the cortical ER

Traffic. 2009 Aug;10(8):1084-97. doi: 10.1111/j.1600-0854.2009.00926.x. Epub 2009 May 12.


Recruitment of cytosolic proteins to individual membranes is governed by a combination of protein-protein and protein-membrane interactions. Many proteins recognize phosphatidylinositol 4,5-bisphosphate [PI(4,5)P(2)] at the cytosolic surface of the plasma membrane (PM). Here, we show that a protein-lipid interaction can also serve as a dominant signal for the sorting of integral membrane proteins. Interaction with phosphatidly-inositolphosphates (PIPs) at the PM is involved in the targeting of the polytopic yeast protein Ist2 to PM-associated domains of the cortical endoplasmic reticulum (ER). Moreover, binding of PI(4,5)P(2) at the PM functions as a dominant mechanism that targets other integral membrane proteins to PM-associated domains of the cortical ER. This sorting to a subdomain of the ER abolishes proteasomal degradation and trafficking along the classical secretory (sec) pathway. In combination with the localization of IST2 mRNA to the bud tip and other redundant signals in Ist2, binding of PIPs leads to efficient accumulation of Ist2 at domains of the cortical ER from where the protein may reach the PM independently of the function of the sec-pathway.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / genetics
  • ATP-Binding Cassette Transporters / metabolism
  • Cell Membrane / metabolism*
  • Endoplasmic Reticulum / metabolism*
  • Green Fluorescent Proteins / genetics
  • Green Fluorescent Proteins / metabolism
  • Liposomes / chemistry
  • Liposomes / metabolism
  • Membrane Lipids / metabolism*
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Phosphatidylinositol 4,5-Diphosphate / metabolism
  • Protein Binding
  • Protein Sorting Signals / genetics
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / genetics
  • Saccharomyces cerevisiae Proteins / metabolism*


  • ATP-Binding Cassette Transporters
  • IST2 protein, S cerevisiae
  • Liposomes
  • Membrane Lipids
  • Membrane Proteins
  • Phosphatidylinositol 4,5-Diphosphate
  • Protein Sorting Signals
  • Recombinant Fusion Proteins
  • STE6 protein, S cerevisiae
  • Saccharomyces cerevisiae Proteins
  • Green Fluorescent Proteins