A mitochondrial carrier is a type of protein found in the inner membrane of mitochondria, the energy-producing organelles in cells. These carriers facilitate the transport of various molecules, such as metabolites and ions, across the mitochondrial membrane, which is crucial for cellular respiration and energy production. These proteins play a vital role in maintaining the balance of substances within mitochondria, ensuring that essential compounds are available for processes like ATP synthesis. By regulating the movement of molecules, mitochondrial carriers contribute to overall cellular metabolism and energy homeostasis, impacting the health and function of cells.