User:DanDupontP/sandbox

Proposed mechanism of power stroke
In the apo-state of dynein, the motor is nucleotide free, the AAA domain ring exists in an open conformation, and the MTBD exists in a high affinity state. Much about the AAA domains remains unknown , but AAA1 is well established as the primary site of ATP hydrolysis in dynein. When ATP binds to AAA1, it initiates a conformational change of the AAA domain ring into the “closed” configuration, movement of the buttress , and a conformational change in the linker . The linker becomes bent and shifts from AAA5 to AAA2 while remaining bound to AAA1  . One attached alpha-helix from the stalk is pulled by the buttress, sliding the helix half a heptad repeat relative to its coilled-coil partner , and kinking the stalk. As a result, the MTBD of dynein enters a low-affinity state, allowing the motor to move to new binding sites. Following hydrolysis of ATP, the stalk rotates, moving dynein further along the MT. Upon the release of the phosphate, the MTBD returns to a high affinity state and rebinds the MT, triggering the power stroke. The linker returns to a straight conformation and swings back to AAA5 from AAA2 and creates a lever-action, producing the greatest displacement of dynein achieved by the power stroke. The cycle concludes with the release of ADP, which returns the AAA domain ring back to the “open” configuration.