Fig. 3.

Truncation of tau at Asp⁴²¹ increases the rate and extent of tau filament assembly in vitro.(A) Kinetic analysis of the assembly of recombinant WT or truncated (1–421) tau proteins into tau filaments in vitro. Tau polymerization was induced by the addition of 75 μM arachidonic acid to 4 μM recombinant WT or truncated tau proteins and measured by right-angle laser light scattering. Scattering intensities were measured on a scale of 0–256 and are proportional to the total mass of polymerized tau filaments (30). The data are presented as the mean ± SEM of three independent experiments. (B) Representative electron micrographs of tau filaments assembled in vitro by recombinant WT tau (Upper) or truncated tau (Lower) proteins. (Bar = 200 nm.)