Figure 3.

Wt and R406W tau exhibit same effective diffusion in the neuritic shaft. (A) Live cell imaging of a PC12 cell coexpressing mRFP-tagged wt tau and PAGFP-tagged R406W tau after fluorescence photoactivation. The position of photoactivation is indicated by a circle in the preactivation images, and distribution between 1 and 112 s was determined. Fluorescence decay of PAGFP-R406W tau in the activated region as a result of diffusion is marked by the arrows. Bar, 20 µm. (B) Fits of representative decay plots to model diffusion of PAGFP-wt tau and R406W tau. Modeling was performed as described in Materials and methods. (C) Effective diffusion coefficients for PAGFP-tau in different combinations of coexpression. Stably transfected PAGFP-tau–expressing lines were transiently transfected with mRFP or mRFP-tagged constructs as indicated. Coexpression of tau constructs reduces the diffusion similarly for wt and R406W tau. Values are shown as mean ± SEM from fits of n processes. Experiments were performed with the 352 tau isoform.