Practice question

Unlike kinesin or myosin where ATP binding induces neck linker docking lever swing generating force dynein power stroke triggered specifically by ATP hydrolysis chemistry within AAA1 site coupling ring closure to linker movement distinct mechanism. Cycle stages: apo or ADP state linker straight spanning ring from tail to opposite side AAA4-5 high affinity microtubule binding strong attachment. ATP binding closes ring but microtubule already detached due to previous allosteric signaling via stalk. Hydrolysis of ATP to ADP Pi inside AAA1 produces large conformational change transmitted via AAA ring helical shifts to linker causing linker to bend from straight to pre power stroke curved configuration storing elastic strain and priming microtubule binding stalk forward position. Pi release closes stalk registry favoring high affinity binding and force generation as linker straightens power stroke dragging cargo toward minus end up to 32 nm power stroke size. ADP release resets motor cycle. Experiments using vanadate ADP Pi analogues trap pre power stroke state showing absolute requirement of hydrolysis rather than just binding to initiate force providing efficiency.