  Cytochrome C oxidase and FoF1-ATP synthase constitute complex IV and V,
respectively, of the five membrane-bound enzymes in mitochondria comprising the
respiratory chain. These enzymes are located in the inner mitochondrial
membrane (IMM), which exhibits large invaginations called cristae. According to
recent cryo-tomography, FoF1-ATP synthases are located predominantly at the rim
of the cristae, while cytochrome C oxidases are likely distributed in planar
membrane areas of the cristae. Previous FLIM measurements (K. Busch and
coworkers) of complex II and III unravelled differences in the local
environment of the membrane enzymes in the cristae. Here, we tagged complex IV
and V with mNeonGreen and investigated their mitochondrial nano-environment by
FLIM and superresolution microscopy in living human cells. Different lifetimes
and anisotropy values were found and will be discussed.
