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. 2004 Jul 27;381(Pt 3):895–904. doi: 10.1042/BJ20040435

Figure 6. Effects of PDZ-binding peptides on protease activity of HtrA1 and HtrA2.

Figure 6

(A) Stimulation of protease activity of HtrA1 by PDZ-binding peptides. BSA (20 μg) was incubated with ΔN-HtrA1 (0.1 μg) or ΔNΔPDZ-HtrA1 (0.02 μg) in a mixture containing 1.5 mM DTT and 0.5 mM of indicated peptides for 1 h. The digests were separated by gel electrophoresis and detected by Coomassie Blue staining (upper panels). Relative protease activity (lower panels) was calculated as described in Figure 4. Closed and open bars indicate protease activity of ΔN-HtrA1 and ΔNΔPDZ-HtrA1 respectively. The amount of ΔNΔPDZ-HtrA1 (0.02 μg) was chosen so that it gave the same protease activity toward reduced BSA as that obtained with 0.1 μg of ΔN-HtrA1. (B) CPIII specifically activated protease activity of HtrA1. BSA (20 μg) was incubated with ΔN-HtrA1(0.1 μg) or ΔN-HtrA2 (0.1 μg) in a mixture containing 1.5 mM DTT and 0.5 mM of indicated peptides for 1 h. Other procedures were as described in (A). Relative protease activity of ΔN-HtrA1 (closed bar) and ΔN-HtrA2 (open bar) are shown in the lower panel.