Figure 3. (A) Localization of the Mutant Amino Acid. Model of the NMHC II-A motor domain (gray) shows the position (red spheres) of amino acid R702 (R709 in II-B). Green spheres in the panel show ATP at the nucleotide binding site. (B) Enzymatic properties of control and mutant NM II HMMs and mouse phenotypes for R702C NM II-A or R709C NM II-B. IVM, in vitro motility; NSM, no significant movement.