Lipid Bilayer Phospholipid Phosphatidylcholine Outside of cell Phosphatidylserine Phosphatidylethanolamine Phosphatidylinositol Cholesterol Inside of cell (cytoplasm SphingolipidLipid Bilayer Phospholipid Phosphatidylcholine Phosphatidylserine Phosphatidylethanolamine Phosphatidylinositol Cholesterol Sphingolipid