Immunocytochemical localization of tropomyosin in rat cerebellum.

A rabbit antiserum against chicken gizzard tropomyosin reacted with two doublets of 30,000 and 40,000 mol. wt., respectively. The heat stability of these polypeptides argued in favour of their being tropomyosins. Immunocytochemical staining of cryostat sections with the antibody showed that tropomyosin was present in glial cells (Bergman glia and oligodendrocytes) and in all identified neuronal cell types in the rat cerebellum. Tropomyosin was not localized homogeneously within neurons, being highly enriched in dendrites and cell bodies in comparison with axons. Myelinated axons of the cerebellar white matter showed only faint staining by the antibody. These results give further evidence for the compartmentalization of cytoskeletal proteins within neurons resulting in major differences in axonal and dendritic cytoskeletons.