FIGURE 4.

Stall force measurements of ATPase mutant dynein in the optical trap. A, schematic representation of the fixed optical trap setup used for stall force measurements in this paper. B, a representative trace of a single AAA4-E/Q dynein motor moving against force in a fixed optical trap at 1 mm ATP (trap stiffness (k) = 0.034 pN/nm). The trace shows a long stall event of ∼1 min, followed by release, which is typical of both wild-type and mutant dynein. C, stall force distributions of wild-type and ATPase mutant dyneins. Stall forces (mean ± S.D.) are 4.5 ± 1.3 pN (n = 132), 2.6 ± 1.2 pN (n = 100), and 3.7 ± 1.2 pN (n = 115) for wild type (WT), AAA3-E/Q, and AAA4-E/Q, respectively. Black lines, Gaussian fit of the data.