Analysis of the motor proteins

Cytoskeletal and motor proteins have extensively been studied in the past. They are involved in diverse processes like cell division, cellular transport, neuronal transport processes, or muscle contraction, to name a few [1, 2]. Three kinds of molecular motor proteins have been identified so far: myosins, kinesins, and dyneins (Figure 1). While kinesins and dyneins move on microtubule tracks (blue lines), myosins are the only motors that use the energy of ATP hydrolysis to power movement along actin filaments (red lines). Especially motor proteins consist of large superfamilies. E.g. vertebrates contain up to 60 myosins and about the same number of kinesins that are spread over more than a dozen distinct classes. Kinesins are in general the smallest motor proteins and mostly perform their task as homodimers. Most of the myosins bind one or more calmodulin-like light chains and thus exists as heteromultimers. The cytoplasmatic dynein/dynactin motor protein complex has a size of about 5 MDa and consists of multiple copies of each of the 17 subunits.

motor proteins in the cell

Figure 1: Schematic representation of an eukaryotic cell, showing the actin (red lines) and microtubule (blue lines) cytoskeleton and different types of the motor proteins.

[1]RD Vale: The molecular motor toolbox for intracellular transport. Cell 2003, 112:467-80.
[2]M Schliwa, G Woehlke: Molecular motors. Nature 2003, 422:759-65.
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