Extended Data Figure 4: Complex V expression is relatively higher than complex IV in the muscle fibre interior.

a, Representative confocal microscopy image of a cross-section of a muscle fibre immunostained for complex IV. b, The same muscle section depicted in a immunostained for complex V. Scale bars, 15 μm. All images analysis was performed on the raw images. Brightness and contrast have been increased for the images shown here to improve presentation. c, Distance map from the boundary of the cell (yellow line) towards the interior of the fibre where image intensity corresponds to distance from the cell boundary. The mean fluorescence signal for all pixels of a given distance from the cell boundary was assessed for both complex IV and complex V. Images representative of 4 fibres from 4 mice. d, Results from intensity profile analysis of 4 muscle fibres from 4 animals show relatively increased complex V in the fibre interior or, conversely, relatively higher complex IV near the fibre periphery. The red, solid line shows the mean intensity profile for complex V from the outside to the inside of the fibre. The green, dotted line shows the mean intensity profile for complex IV from the outside to the inside of the fibre. Values are normalized to the maximal intensity from each intensity profile to allow comparison of images of varying intensities. Grey shading around each line shows the standard error.