TY - JOUR
T1 - Intramembrane aspartic acid in SCAP protein governs cholesterol-induced conformational change
AU - Feramisco, Jamison D.
AU - Radhakrishnan, Arun
AU - Ikeda, Yukio
AU - Reitz, Julian
AU - Brown, Michael S.
AU - Goldstein, Joseph L.
PY - 2005/3/1
Y1 - 2005/3/1
N2 - 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.
AB - 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.
KW - Insig
KW - Membrane proteins
KW - Sterol regulatory element-binding protein
UR - http://www.scopus.com/inward/record.url?scp=14744272151&partnerID=8YFLogxK
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U2 - 10.1073/pnas.0500206102
DO - 10.1073/pnas.0500206102
M3 - Article
C2 - 15728349
AN - SCOPUS:14744272151
SN - 0027-8424
VL - 102
SP - 3242
EP - 3247
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 9
ER -