FIGURE 6.
Tmod1 and Tmod3 cap platelet β/γcyto-actin pointed ends similarly with TM5NM1. A, pyrene-actin polymerization kinetics depicting platelet β/γcyto-actin elongation from the pointed ends of CapZ-capped β/γcyto-actin filaments in the presence of TM5NM1 and two different concentrations of Tmod1 or Tmod3. Concentrations of proteins were: 1.8 μm G-actin (8% pyrene-labeled), CapZ-F-actin seeds (1:100; 1.6 nm CapZ, 160 nm β/γcyto-actin), and Tmods and TMs as indicated. B, the pointed (P) end capping activities of Tmod1 and Tmod3 were evaluated by measuring their ability to inhibit the initial rates of β/γcyto-actin elongation from the pointed ends of CapZ-capped actin filaments in the presence of TM5NM1 and either Tmod1 or Tmod3. 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. AU, arbitrary units.