A B Figure 9.44 Experimental demonstration of the dynamic character of intermediate fila- ments. These photographs show the results of an experiment in which biotin-labeled type I keratin was microinjected into cultured epithelial cells and localized 20 minutes later using immunofluorescence. The photograph in a shows the localization of the injected biotinylated keratin(as revealed by anti-biotin antibodies) that had become incorporated into filaments during the 20-minute period following injection. The photograph in b shows the distribution of intermediate filaments in the cell as revealed by anti-keratin antibodies. The dotlike pattern of fluorescence in a indicates that the injected subunits are incorporated into the existing fila- ments at sites throughout their length, rather than at their ends.(Compare with a similar ex- R以c versity Press
intermediate filaments desmosome connecting two cells 9O B 20
