Intramembrane aspartic acid in SCAP protein governs cholesterol-induced conformational change

Jamison D. Feramisco, Arun Radhakrishnan, Yukio Ikeda, Julian Reitz, Michael S. Brown, Joseph L. Goldstein

Research output: Contribution to journalArticlepeer-review

35 Scopus citations


The polytopic membrane protein SCAP transports sterol regulatory element-binding proteins (SREBPs) from the endoplasmic reticulum (ER) to the Golgi, thereby activating cholesterol synthesis. Cholesterol accumulation in the ER membranes changes SCAP to an alternate conformation in which it binds ER retention proteins called Insigs, thereby terminating cholesterol synthesis. Here, we show that the conserved Asp-428 in the sixth transmembrane helix of SCAP is essential for SCAP's dissociation from Insigs. In transfected hamster cells, mutant SCAP in which Asp-428 is replaced by alanine (D428A) remained in an Insig-binding conformation when cells were depleted of sterols. As a result, mutant SCAP failed to dissociate from Insigs, and it failed to carry SREBPs to the Golgi. These data identify an important functional residue in SCAP, and they provide genetic evidence that the conformation of SCAP dictates the rate of cholesterol synthesis in animal cells.

Original languageEnglish (US)
Pages (from-to)3242-3247
Number of pages6
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number9
StatePublished - Mar 1 2005


  • Insig
  • Membrane proteins
  • Sterol regulatory element-binding protein

ASJC Scopus subject areas

  • General


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