Macrophages contain at least two myosins.

A number of motile functions of macrophages are thought to be mediated by myosin. We have observed that myosin from rabbit alveolar macrophages is heterogeneous with respect to its 20 kDa light chain: two species of 20 kDa light chain are identified by one-dimensional and two-dimensional polyacrylamide gel electrophoresis, in a ratio of 2:1. Native myosin, analyzed on non-denaturing gels, is also composed of two species, in a ratio of 2:1. These results indicate that macrophages contain at least two different myosins, which might have different physiological functions.