Working Model of ATP Synthase

This molecular machine is the main source of energy for most organisms. This model represents the ATP synthase in our mitochondria, has 243 pieces and is about 10 million times the size of the original. At this scale a water molecule would be about the height of a lego plate. In one of our cells there are around a million of these machines rotating up to 300 times per second. During the day all the ATP synthases in our body produce over 50 kg of ATP which is consumed as fast as it is made, to power our muscles, neurons and everything else, so that at any time we only have about 50 grams of the stuff. 

The rotor embedded in the membrane (blue) rotates when protons move from the lower side, where they are more abundant, to the upper side through the green subunit. The head, supported by the peripheral stalk (white) has 3 regulatory subunits (dark red) and 3 active subunits (red). These produce ATP by fusing ADP with P as the rotating central stalk (tan) pushes them to open and close.