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Annu Rev Biochem. 2018 Jun 20;87:809-837. doi: 10.1146/annurev-biochem-061516-044924. Epub 2018 Mar 29.

The Oxysterol-Binding Protein Cycle: Burning Off PI(4)P to Transport Cholesterol.

Author information

1
Institut de Pharmacologie Moléculaire et Cellulaire, CNRS UMR 7275, Université Côte d'Azur, 06560 Valbonne, France; email: antonny@ipmc.cnrs.fr.

Abstract

To maintain an asymmetric distribution of ions across membranes, protein pumps displace ions against their concentration gradient by using chemical energy. Here, we describe a functionally analogous but topologically opposite process that applies to the lipid transfer protein (LTP) oxysterol-binding protein (OSBP). This multidomain protein exchanges cholesterol for the phosphoinositide phosphatidylinositol 4-phosphate [PI(4)P] between two apposed membranes. Because of the subsequent hydrolysis of PI(4)P, this counterexchange is irreversible and contributes to the establishment of a cholesterol gradient along organelles of the secretory pathway. The facts that some natural anti-cancer molecules block OSBP and that many viruses hijack the OSBP cycle for the formation of intracellular replication organelles highlight the importance and potency of OSBP-mediated lipid exchange. The architecture of some LTPs is similar to that of OSBP, suggesting that the principles of the OSBP cycle-burning PI(4)P for the vectorial transfer of another lipid-might be general.

KEYWORDS:

LTP; MCS; ORP; OSBP-related protein; PI(4)P; Sac1 lipid phosphatase; VAMP-associated protein; VAP; lipid transfer protein; membrane contact site; phosphatidylinositol 4-phosphate

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