Relay helix. A superposition of key elements in two forms of scallop myosin reveals the structural changes that are transmitted by the relay helix from the switch I and switch II loops to the base of the lever arm. Notice that the switch I and switch II loops interact with VO₄³⁻ in the position that would be occupied by the γ-phosphoryl group of ATP. The structure of the myosin–ADP–VO₄³⁻ complex is shown in lighter colors.

[Drawn from 1DFL.pdb and 1SR6.pdb.]