Seeds need fuel to germinate and grow into plants. They get this fuel from oil bodies. Oil bodies are micelles that package hydrophobic triacylglycerides (TAGs) or “fat” within seeds. The outer membrane contains phospholipids and proteins which have hydrophilic and hydrophobic ends. Oleosins are the most prominent protein imbedded in the membrane of the oil body. Both ends of the protein are hydrophilic and sit on the outside of the membrane along with the phospholipid heads. There is a central hydrophobic domain that inserts into the membrane anchoring the protein. The hydrophobic domain contains a highly preserved proline knot motif that creates a hairpin turn and sends the other end of the protein back through the membrane. Despite the understanding of the localisation and primary structure of oleosins the function and secondary structure have been a mystery. Using plant biochemistry I have investigated the function of the different domains of oleosins and discovered how the interactions oleosin makes with other oleosins and other proteins in the cytoplasm to carry out its function.