2.2 Movement Using Biological Molecules and Methods

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Figure 2.4: The mechanism of cellular transport on a microtubule. A-E: a stiff protein subunit binds to

the microtubule, moves for a short distance using force, using ATP as energy. The subunit then releases,

moving to the next location, completing a step. F-G: Different motors coordinate the steps in different ways

(adapted from [10]).

2.2 Movement Using Biological Molecules and Methods

Figure 2.3 [9] suggests the most common use of biological motor proteins: carrying cargo

in a controlled manner on a track in the nanoscale. The track is the actin or microtubule

fiber, the motor protein (myosin, kinesin, and dynein are the most common ones, but

bacterial motors are used as well) should be controllable, and the cargo can be anything

with the right size scale that binds to the motor proteins [9] (Figure 2.5). Ideally, the

system should be easy to assemble and then remain stable.

This is where things become a bit more complicated: The track needs to first be as-

sembled somehow. The cell does this actively when needed in the directions needed;