Mitochondria are associated with n intermediate filaments in cultured I (triple immunofluorescent labeling/vimentin/tubulin/cytochrome c o

Triple-immunofluorescence experiments with antibodies to cytochrome c oxidase, tubulin, and vimentin have been used to immunolabel the mitochondria, microtubules, and intermediate filaments inside the same cultured fibroblasts. In particular, fibroblasts were immunolabeled after they had either been transformed by infection with Rous sarcoma virus or given long-term treatment with cycloheximide. These treatments in- duced redistribution of the intermediate filaments into a perinu- clear arrangement, segregated away from the microtubules, which remained extended to the cell periphery. In such cells, many labeled mitochondria were observed to be codistributed with the peripherally located microtubules. From these results, we infer that an association, probably involving some type of chemical link- age(s), between mitochondria and microtubules exists in these cells that is independent of the intermediate filaments.