FIGURE 1.

Location and alternative sequence choices for the exon 7 region. The exon 7 region (red) and the three other variable regions (3, 9, and 11) encoded by Drosophila alternative exons (green) are mapped onto the chicken myosin S1 structure (gray). The exon 7 region is part of one lip of the nucleotide entry/exit site (14). The long α-helix that binds the light chains and constitutes the lever arm is across the top of the figure and the actin binding sites are at the bottom right. The EMB (7a) and IFI (7d) amino acid sequence versions of the exon 7 region are shown below the molecular structure. Asterisks signify nonconserved substitutions.