Figure 1.

Reversals of Purified Phagosomes and Phagosomes inside Cells in an Optical Trap

(A) Position-time traces of two EPs in an optical trap. A schematic (not to scale) depicts orientation of MT with an EP (sphere) in the trap (red). Transitions between dynein and kinesin are indicated. For example, KD depicts a kinesin stall followed by a dynein stall. Inactive periods (yellow boxes) are when the EP sits at the trap center. Reversals with an intervening inactive time of <0.5 s are labeled as RRs (rapid reversals, see text). All reversals in this particular figure are RRs.

(B) Bar graph depicting the fractional occurrence of different types of event pairs DD, DK, KK, and KD. A total of 447 event pairs were analyzed. Actual number of events-pairs observed for each type is indicated. The 25% level is indicated. Error bar, SEM.

(C) Fractional occurrence of head (H) and tail (T) event pairs in computer-simulated tossing of a fair coin.

(D) Stalls of latex bead phagosomes inside a J774.2 cell (mouse macrophage). RR events for DK and KD event pairs are marked. T_STALL is the width of a stall force record at half-maximal force.

(E) Stalls on latex bead phagosomes inside a J774.2 cell, followed by reversals and escape from the trap.

See also Figures S1 and S3.