Catalyzes the transfer of phosphatidylinositol, phosphatidylcholine and sphingomyelin between membranes (By similarity). Required for COPI-mediated retrograde transport from the Golgi to the endoplasmic reticulum; phosphatidylinositol and phosphatidylcholine transfer activity is essential for this function (By similarity).
Subcellular locations: Golgi apparatus, Golgi apparatus membrane, Endoplasmic reticulum membrane