OSBP
Domain
The FFAT motif is required for interaction with VATA and proper localization of the protein.
The PH and the Ala/Gly-rich domains control cholesterol binding without affecting 25-hydroxycholesterol binding.
The second coiled-coil domain is required for interaction with the tyrosine phosphatase.
Function
Lipid transporter involved in lipid countertransport between the Golgi complex and membranes of the endoplasmic reticulum: specifically exchanges sterol with phosphatidylinositol 4-phosphate (PI4P), delivering sterol to the Golgi in exchange for PI4P, which is degraded by the SAC1/SACM1L phosphatase in the endoplasmic reticulum (PubMed:24209621). Binds cholesterol and a range of oxysterols including 25-hydroxycholesterol (PubMed:15746430, PubMed:17428193). Cholesterol binding promotes the formation of a complex with PP2A and a tyrosine phosphatase which dephosphorylates ERK1/2, whereas 25-hydroxycholesterol causes its disassembly (PubMed:15746430). Regulates cholesterol efflux by decreasing ABCA1 stability (PubMed:18450749).
Sequence Similarities
Belongs to the OSBP family.
Tissue Specificity
Widely expressed.
Cellular localization
- Cytoplasm
- Cytosol
- Cytoplasm
- Perinuclear region
- Golgi apparatus membrane
- Peripheral membrane protein
- Endoplasmic reticulum membrane
- Peripheral membrane protein
- Golgi apparatus
- trans-Golgi network
- Predominantly cytosolic.
Alternative names
OSBP1, OSBP, Oxysterol-binding protein 1