EXPERIMENTAL FIGURE 17-6 Myosin S1 decoration demonstrates the identity and polarity of an actin filament. Myosin S1 head domains bind to actin subunits in a particular orientation. When bound to all the subunits in a filament, S1 appears to spiral around the filament. This coating of myosin heads produces a series of arrowhead-like decorations (arrows). The polarity in decoration defines a pointed (−) end and a barbed (+) end.

[Courtesy of Roger Craig, University of Massachusetts Medical School.]