Membrane-bound O-acyltransferase involved in the remodeling of glycosylphosphatidylinositol (GPI) anchors. Acts only on GPI-anchored proteins, but not on free GPI lipids. Also involved in lipid metabolism, having profound effects on sphingolipid-sterol-ordered domains integrity and assembly. Involved in cell integrity and apoptosis. Belongs to the membrane-bound acyltransferase family.