FIGURE 3.

Molecular model of scallop myosin S2 (17). Each chain of the coiled-coil has the same 43 amino acids shown at the top of the figure and the amino acids numbers run from 843 to 885. The heptads are separated by vertical red bars and the unusual a, d, and g residues are underlined by black bars. The C-chain is shown with the side chains colored as follows: red, acidic; blue, basic; yellow, hydrophobic; green, polar. The D-chain is shown simply as an α-helical coil for simplicity. This orientation is the E0 for the different modes of stretching shown in Figs. 7, B and C, and 8, B and C.