If a delivery person leaves a package on your front step without pinging you, you likely won’t know it’s there. A hungry cell awaiting refuel is in a similar position. It has to be alerted to the presence of nutrients outside of the cell wall by a sensing mechanism so that a transporter protein can bring the nourishment inside. The small number of these nutrient-sensing mechanisms thus far identified have had a profound impact on human health. One prime example is the discovery of the nutrient-sensing mechanism for cholesterol, which led to the development of life-saving statin drugs (and the Nobel Prize). These discoveries have focused on how an entire cell detects nutrients. But within every human cell are self-contained, membrane-bound organelles, all of which are equally in need of fuel to carry out important functions. Might they, then, have nutrient sensors of their own?