MITO-ID® Red detection (ENZ-51007) and MITO-ID® Green Detection kit (ENZ-51002) appear to target the inner mitochondrial membrane in mammalian cells, which contains a highly specialized anionic phospholipid, cardiolipin. Cardiolipin represents approximately 20% of the total lipid composition in the inner mitochondrial membrane, where it is essential for the optimal function of numerous enzymes that are involved in mitochondrial energy metabolism. Accumulation of these probes in mitochondria is largely independent of the mitochondrial membrane potential.