FIGURE 1.

The interactions between the GTD dimer and between Myo5a-GTD and Mlph-GTBDP. A, cartoon representation of the Myo5a-GTD structure (Protein Data Bank code 3WB8) showing a head to tail dimer. There are four putative dimers in the crystal structure of mouse Myo5a-GTD, and only one dimer (chains a and c) is shown here. B, cartoon representation of Myo5b-GTD structure (Protein Data Bank code 4J5M) showing a head to head dimer. C, cartoon representation of the Myo5a-GTD·Mlph-GTBDP complex structure (Protein Data Bank code 4LX2). SD-1 and SD-2 indicate subdomains 1 and 2 of the GTD, respectively. Sticks show the residues at the GTD-GTD interface and the interface between Myo5a-GTD and Mlph-GTBDP. Spheres show the two conserved basic residues Lys¹⁷³⁰ and Lys¹⁸⁰³, which are essential for inhibiting motor function (7). In the head to tail model of the GTD dimer, the distances between the two Lys¹⁷³⁰ and between the two Lys¹⁸⁰³ are 79 and 66 Å, respectively. In the head to head model of the GTD dimer, the distances between the two Lys¹⁷³⁰ and between the two Lys¹⁸⁰³ are 153 and 142 Å, respectively. For clarity, all residue numbers refer to the melanocyte isoform of Myo5a (see “Experimental Procedures” for details).