Fig. 7.

Possible mechanism for dynein movement. (A) Head-class averages characteristic of each nucleotide state are selected from Fig. 5 A and B, and aligned by their A-MT attachment sites (yellow dotted line). In #2 and #3, at least one ring is shifted toward the minus end (red dotted line). (B) Stalk-class averages are superimposed on the head-class averages (red) shown in A to show both stalks and tails clearly. The stalks do not rotate but, together with their heads, shift ≈8 nm (cyan dotted line) toward the minus end in some ADP·Vi averages. (C) A model for dynein stepping (see “Mechanism of Motility” in Results and Discussion). (Scale bar: 10 nm.)