Kinesin-1 carries cargo along microtubules toward their plus ends. Two identical heads take turns: the rear head swings past the bound head and lands 16 nm ahead. The motor moves 8 nm and spends one ATP for each step. It makes about 100 steps before it lets go.
8 nm
Centre-of-mass step, the length of one tubulin dimer. Later studies measured 8.1-8.3 nm (Coy et al. 1999; Nishiyama et al. 2002).
17.3 ± 3.3 nm
Each head moves about twice the centre-of-mass step. Heads alternate: hand-over-hand.
1
Tight coupling at near-zero load, and over a wide range of loads.
about 800 nm/s
One turnover takes about 10 ms.
about 1 µm
1.12 µm at zero load, from a fit over hindering loads. That is more than 100 steps per encounter with the microtubule.
5-7 pN
5.4 ± 1.0 pN against a glass fibre; 5-6 pN in an early optical trap; about 7 pN in a later one (Carter and Cross 2005). Stall force rises with ATP concentration (Visscher et al. 1999).
about 60 µM
Microtubule gliding by sea urchin kinesin. Opposing load raises the apparent Km (Visscher et al. 1999).
about 13-15 residues
The segment after helix α6 that docks onto the head. Papers draw its boundaries differently, so the count varies.