Conformational changes in the motor domain associated with ADP-Mg ²⁺ release. Comparisons of the nucleotide-free rigor form and Mg²⁺·ADP-bound complex reveal conformational changes associated with ADP release. (A) Comparison of the S1 motor domains of the nucleotide free-rigor form (orchid) and the Mg²⁺·ADP-bound complex are shown in two different orientations. We highlight significant portions of the motor domain that change from between the models including the converter domain, relay helix, N-terminus, and the lever arm. (B) Individual panels show the conformational differences in more detail for the specified regions. Small differences at the nucleotide-binding site are linked to these larger movements of subdomains. The converter domain change was measured from the α-carbon of residue S747. The lever arm rotation was measured using the axes, planes, and ellipsoids tool in Chimera. The axes used in the calculation were defined as the last 13-resiudes of the lever arm. The relay helix change was measured by the change in the α-carbon of E504.