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. 2022 Mar 29;119(14):e2113520119. doi: 10.1073/pnas.2113520119

Fig. 3.

Fig. 3.

Proteolysis of tau protein. (A) Left, proteolysis of soluble tau. 5 µM tau was incubated with 0.5 µM HTRA1 or 0.5 µM CAPN2 or with HTRA1 CAPN2 at 37 °C in 50 mM Tris HCl, pH 8. Samples were taken at the time points indicated and analyzed by SDS-PAGE. Right, proteolysis of tau fibrils. Digests were performed as described for soluble tau except that 2.5 µM final concentration of tau fibrils and HTRA1/HTRA1-CAPN2 were used. (B) Sedimentation assay of tau fibrils. Tau fibrils were incubated with equimolar amounts of proteolytically inactive HTRA1 S328A (HTRA1SA) or CAPN2 or HTRA1 CAPN2 followed by ultracentrifugation. Subsequently, samples before centrifugation (T, total) of pellet (P) and supernatant (S) fractions were subjected to SDS-PAGE and Coomassie staining. *CAPN2 fragment. Note that CAPN2 does not digest tau because the buffers used did not contain Ca2+.