F1-ATPase: A Rotary Motor Made
of a Single Molecule
To
observe rotation, the three β
subunits were fixed on a glass surface through histidine tags
engineered at the N terminus. To the putative rotor subunit
γ, a μm-sized
actin filament was attached through streptavidin. When ATP
was added, the actin filament rotated continuously clockwise
(movie). Note that, in this movie, the rotation occurs
around the middle of the filament. If you hold an end of a
long rod, you could make a fake rotation by twisting your
wrist. If you hold the middle, however, you have to rotate
yourself to keep the rod rotating. Thus, the propeller
rotation in this movie shows that the γ subunit really slides
against the surrounding α3β3 subunits over
infinite angles.
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