
Molecules that have a regular “day job” in the normal function of the cell must also be ready to act differently in case of an emergency. The mitochondrion (the football-shaped structure in the middle) is the power plant of the cell. Cardiolipin (CL) is a special type of fat that normally functions as part of a team of molecules on the inner mitochondrial membrane to generate a type of energy called ATP. This process is important, but also dangerous (think of a car that uses gasoline—the gasoline can be very useful to power the car, but if it leaks out of the tank it could be a problem). If the mitochondrion is damaged, risking the leakage of harmful molecules, CL travels to the outer surface of the mitochondrion to send “help me” signals that are recognized by a protein called LC3. LC3 packages broken pieces of the damaged power plant into autophagosomes (yellow bag) so that its components can be recycled. This process is called "autophagy" - which means "self-eating." doi:10.1038/ncb2837.