Regulates cellular transport and efflux of cholesterol (By similarity). Plays a role in phosphatidylinositol-4-phophate (PI4P) turnover at the neuronal membrane (PubMed:30028970). Binds via its PH domain PI4P, phosphatidylinositol-4,5-diphosphate, phosphatidylinositol-3,4,5-triphosphate, and phosphatidic acid (PubMed:30028970). Weakly binds 25-hydroxycholesterol (By similarity). Homodimer (PubMed:30028970). Interacts with OSBPL3 (PubMed:30028970). Co-localizes with OSBPL3 at contact sites between the plasma membrane and the endoplasmic reticulum. Expressed in skin, respiratory epithelium, small intestine epithelium, pancreas, striated muscle, brain, spinal ganglia, and nervous plexus of the intestine (at protein level) (PubMed:14593528, PubMed:30028970). In the brain, specifically in the cerebellum, it is expressed in Purkinje and granule cells (PubMed:30028970). Expressed in hepatocytes and macrophages (PubMed:26941018). Detected in the brain at 18.5 days post coitum (dpc), with expression increasing till it reaches its peak expression at 28 dpc. By acetylated low-density lipoprotein and dietary intake of cholesterols. Belongs to the OSBP family.