The neutral lipids, TG and cholesterol ester, are synthesised by ER membrane proteins. These lipid molecules then coalesce to form the core of a lens-shaped structure that protrudes towards the cytoplasm. The nascent LD buds off from the ER membrane to form the mature cytoplasmic organelle. Abbreviations: ATGL, adipose triglyceride lipase; DG, diacylglycerol; DGAT, diacylglycerol acyl-transferase; FA-CoA, fatty acyl-CoA; HSL, hormone-sensitive lipase; MG, monoacylglycerol; MGAT, monoacylglycerol acyl-transferase; MGL, monoacylglycerol lipase; PA, phosphatidic acid; PAP, phosphatidic acid phosphatase; PL, phospholipids.