Interacts with OSBPL11 to function as lipid transfer proteins (PubMed:39106189). Together they form a heterodimer that localizes at the ER-trans-Golgi membrane contact sites, and exchanges phosphatidylserine (1,2-diacyl-sn-glycero-3-phospho-L-serine, PS) for phosphatidylinositol-4-phosphate (1,2-diacyl-sn-glycero-3-phospho-(1D- myo-inositol 4-phosphate), PI(4)P) between the two organelles, a step that is critical for sphingomyelin synthesis in the Golgi complex (PubMed:39106189). Interacts with OSBPL10 to function as lipid transfer proteins (PubMed:36853333). Together they form a heterodimer that localizes at the ER-trans-Golgi membrane contact sites, and exchanges phosphatidylserine (1,2-diacyl-sn-glycero-3-phospho-L-serine, PS) for phosphatidylinositol-4-phosphate (1,2-diacyl-sn-glycero-3-phospho-(1D- myo-inositol 4-phosphate), PI(4)P) between the two organelles, a step that is critical for sphingomyelin synthesis in the Golgi complex (PubMed:36853333). {ECO:0000269|PubMed:36853333, ECO:0000269|PubMed:39106189}. This is the function of ENSG00000117859 (OSBPL9, oxysterol binding protein like 9).