To be more specific, this is the F0F1 Mitochondrial ATP Synthase. This protein is the reason that I decided to study biochemistry, but I have to say that this animation doesn't nearly do it justice. For one thing, the entire rotor/stator mechanism of the F0 unit is woefully glossed over. The rotor itself is composed of a number of alpha-helices that have a single location for a motile hydrogen to attach. In doing so, it causes a rotation of the lower half of the helix, generating a mechanical motion that turns the rotor.

In fact, probably the most amazing aspect of this protein is that it is, in every sense of the term, a nano-machine. ATP is generated not by chemical reaction, but rather by mechanical force. The 3 active sites in the F1 unit have residues which hold the ADP and Pi in a favorable arrangement, but it is the spring action, triggered by the crankshaft, that causes a vice-like movement that literally squeezes the two together to form ATP.

Very cool...if you ask me.