-
All eukaryotic cells including those of our body contain a large variety
of molecular machines that fulfill many different functions: Stepping motors, which run
along cytoskeletal filaments with about 100 steps per second; Rotary motors, which revolve
with about 100 Hz;
Membrane pumps, which transport ions against concentration gradients; Molecular
assemblers such as polymerases and ribosomes; see
motor cartoons.
All of these motors use chemical free energy, typically released by nucleotide
hydrolysis, to generate mechanical forces.
-
Even though cytoskeletal motors are rather small and constantly collide with many
water molecules, they perform
directed transport over many length scales
as reviewed in
[1,
2,
3].
This multiscale motility involves the following aspects:
-
Cytoskeletal motors move along
microtubules and actin filaments
that are formed by the self-assembly of tubulin dimers and actin
monomers, respectively. Because the associated assembly and disassembly
processes are also coupled to nucleotide hydrolysis, these processes can
generate mechanical forces as well. For our recent results on actin filaments,
see
-
Cytoskeletal filaments are built up from a large number of protein
molecules that all belong to the same protein species.
The cell also contains chemically much more complex molecular machines such as
ribosomes,
which consist of several strands of rRNA as well as a large number
of different proteins.
Ribosomes move along mRNA molecules and translate the
codon sequences of these mRNAs into proteins, see
|
|
