Dictostelium discoidium

The myosin motor is an ATPase, because it is driven by cyclic ATP binding to cause detachment, splitting to form ADP and Pi, and the sequential release initially of Pi with contraction and then of ADP in readiness for a new ATP to bind. The organism Dictostelium discoidium provides a convenient motor domain for studying muscle contraction because of its near identity to the myosin motor of skeletal muscle. 

Figure 1.5. The waters of Thales of the myosin II motor. Stereo views of the crystal structure of the myosin motor domain of Dictostelium discoidium in presence of ATP are shown. A Space-filling display showing water molecules on a sculptured surface of the myosin II motor. B Those water molecules throughout the entire structure that are sufficiently fixed in space to be seen by X-ray diffraction are...

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