Thesis-PDF - IAP/TU Wien
Thesis-PDF - IAP/TU Wien
Thesis-PDF - IAP/TU Wien
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Figure 4.15: Kinesin and dynein and their direction of propagation along<br />
a microtubule. Kinesin has a remarkable way of moving by using the handsover-hands<br />
method. Its two heads pass over another when the protein moves<br />
along the tube. In this way it is similar to the human walking style, putting<br />
one foot in front of the other. Scale bar is 50nm. Image adapted from [102].<br />
precisely regulated, such that a complex concerted action like euglenoid movement<br />
is made possible.<br />
Besides providing the pellicle with dynamic properties one major area of microtubule<br />
usage can be found in the flagellum. The core structure of Euglena’s<br />
flagellum consists of nine outer doublets of microtubli and one inner doublet. The<br />
cross section of such an arrangement shows that each outer doublet has a dynein<br />
protein attached to it, enabling the flagellum to actively slide within its shaft. This<br />
basic mechanism is responsible for the typical flagellar ondulatory movement.<br />
A very interesting fact about the Euglena pellicular strip is their assembly<br />
process. Instead of being transferred and attached in part to the plasma membrane,<br />
they are assembled molecule by molecule. The location where the individual<br />
proteins bind is directed by special binding sites spread on the inner side of<br />
the plasma membrane. The membrane skeleton (pellicle) of Euglena is primarily<br />
assembled from a 80 kDa 12 membrane skeletal protein binding to the plasma<br />
membrane through noncovalent interactions with a small cytoplasmic domain of<br />
the plasma-membrane protein IP39. ([101])<br />
The pellicle, or membrane skeleton, underlying the plasma membrane plays a<br />
12 A dalton (Da or D) is a unit of mass, equivalent to the unified atomic mass unit (u). It is<br />
defined to be one twelfth of the mass of an unbound atom of the carbon-12 nuclide, at rest and<br />
in its ground state. 1kDa = 1000 Da. E.g. a caffeine molecule has a mass of 194 Da.<br />
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