Reaction: OSBP exchanges 25OH-CHOL with PI4P from ER membrane to Golgi membrane
- in pathway: Synthesis of bile acids and bile salts
Oxysterol-binding protein 1 (OSBP) is involved in lipid countertransport between the Golgi and the ER membranes. It specifically exchanges sterols such as 25-hydroxycholesterol (25OH-CHOL) with phosphatidylinositol 4-phosphate (PI4P), delivering it to the Golgi in exchange for PI4P, which is degraded by the SAC1/SACM1L phosphatases in the ER. The PH-FFAT region of OSBP is necessary for membrane tethering, which then directs forward sterol and backward PI4P transport by the ORD domain of OSBP (Mesmin et al. 2013).
Reaction - small molecule participants:
25OH-CHOL [Golgi membrane]
PI4P [endoplasmic reticulum membrane]
25OH-CHOL [endoplasmic reticulum membrane]
PI4P [Golgi membrane]
Reactome.org reaction link: R-HSA-8868402
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Reaction input - small molecules:
25-hydroxycholesterol
1-phosphatidyl-1D-myo-inositol 4-phosphate
Reaction output - small molecules:
25-hydroxycholesterol
1-phosphatidyl-1D-myo-inositol 4-phosphate
Reactome.org link: R-HSA-8868402