Visualization of protein diffusion in mitochondria. (A and B) Representative images from photoconversion experiments in fis1∆ cells expressing Tom20-2×Kaede in the absence of matrix-targeted fluorescence proteins (A) and fis1∆ cells expressing matrix-2×Kaede (B). (C) Quantification of converted-to-nonconverted Kaede fluorescence ratios (red/green) in the mother compartment compared with the bud compartment using Tom20-2×Kaede (n = 17 cells) or matrix-2×Kaede (n = 17 cells). Photoconversion was applied as indicated with white circles with 15 imaging-photoconversion cycles (10 s/cycle). The line graphs are the intensity profiles along the lines in the respective images after photoconversion. Images are a sum projection of five z-stacks taken at 0.5 μm intervals. Scale bar: 3 μm. Error bar: mean ± SE. Welch’s two-tailed t test was applied to compare the conversion ratios between two groups.