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Table I.

Motility and ATPase properties of constructs used in this study

ConstructsSingle molecule
Gliding
ATPase activity
Velocity
Run length
Velocity
kcat
Km MT
 μm/s μm μm/s ATPs/s/head μM 
Osm-3 RD RD 0.32 ± 0.06 4 ± 1 0.23 ± 0.02 
K530 0.7 ± 0.3 1.2 ND 29 ± 6 0.29 ± 0.08 
K-O 0.5 ± 0.2 0.4 0.30 ± 0.07 33 ± 5 0.20 ± 0.10 
O-K 1.5 ± 0.3 2.6 0.48 ± 0.08 75 ± 9 0.13 ± 0.09 
OSM-3–ΔH2 0.8 ± 0.2 1.9 0.80 ± 0.10 69 ± 5 0.21 ± 0.06 
OSM-3–G444E 1.1 ± 0.2 1.4 0.91 ± 0.09 75 ± 2 0.30 ± 0.10 
ConstructsSingle molecule
Gliding
ATPase activity
Velocity
Run length
Velocity
kcat
Km MT
 μm/s μm μm/s ATPs/s/head μM 
Osm-3 RD RD 0.32 ± 0.06 4 ± 1 0.23 ± 0.02 
K530 0.7 ± 0.3 1.2 ND 29 ± 6 0.29 ± 0.08 
K-O 0.5 ± 0.2 0.4 0.30 ± 0.07 33 ± 5 0.20 ± 0.10 
O-K 1.5 ± 0.3 2.6 0.48 ± 0.08 75 ± 9 0.13 ± 0.09 
OSM-3–ΔH2 0.8 ± 0.2 1.9 0.80 ± 0.10 69 ± 5 0.21 ± 0.06 
OSM-3–G444E 1.1 ± 0.2 1.4 0.91 ± 0.09 75 ± 2 0.30 ± 0.10 

Motor protein constructs were purified, and assays were conducted as described in Materials and methods. For motility data, >100 measurements were taken from at least two protein preparations. Velocities shown represent the mean and SD. Run lengths were corrected for photobleaching (Thorn et al., 2000), and the indicated mean run lengths were determined by fitting run length histograms to an exponential decay function. The mean and SD of the ATPase data were derived from three to nine assays (as shown in Fig. S1) using two to four protein preparations. RD, rarely detected; Osm-3 did not exhibit consistent processive motion (only a few short runs detected in >30 min of observation; consistent for five protein preparations). MT, microtubule.

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