After dissociation of the connection subdomain, the fingers/palm subdomains rotate away from each other, and the palm C-terminus forms a short, amphiphilic β-sheet that lies against the palm domain β-sheet (β6-β9-β10). The tips of the fingers and thumb form a weak interface that helps to position the system for dimer formation. A ribbon diagram of the fingers – thumb interface is shown at the upper right. The initial p66/p66' homodimer is a structural heterodimer that is formed from a p66E-like structure and the p66M monomer structure. The ribbon diagram to the lower left corresponds to the initial homodimer with color-coded p66' subdomains; in the ribbon diagram to the lower right, the p66 subdomains are color coded, and the overlaid initial connection domain conformation is indicated in light pink.