FIGURE 5.
Tmod1 and Tmod3 cap αsk-actin pointed ends similarly over a range of TM concentrations for α/βTM, TM5NM1, and TM5b. A–C, the pointed (P) end capping activities of Tmod1 and Tmod3 were evaluated by measuring their ability to inhibit the initial rates of αsk-actin elongation from the pointed ends of CapZ-capped actin filaments in the presence of the increasing amounts of α/βTM (A), TM5b (B), or TM5NM1 (C). Concentrations of proteins were: 1.8 μm G-actin (8% pyrene-labeled), 1.6 nm CapZ-F-actin seeds (1:100; 1.6 nm CapZ, 160 nm αsk-actin), and Tmods and TMs as indicated. The pointed end capping efficiency is plotted as (1 − Rate/Control rate) × 100 (%). Thus, when rate/control rate = 0, 100% of pointed ends are capped. Data shown are mean ± S.D. (error bars) of three experiments.