Light chains of chicken embryonic gizzard myosin.

1. Myosin from gizzards of 15-day-old chicken embryos was highly purified by ammonium sulfate fractionation in the presence of ATP and MgCl2, ultra-centrifugation and Sepharose 4B chromatography. 2. The myosin composed of heavy and three light chains as determined by sodium dodecyl sulfate (SDS) gel electrophoresis. The molecular weights of the light chains were 23,000 (L23), 20,000 (L20), and 17,000 (L17), respectively. The amount of L23 light chain decreased and disappeared, and the L17 light chain increased steadily in the course of development. The amount of L20 light chain did not change. 3. ATPase activity of the embryonic myosin was essentially the same as that of adult myosin. The change in the light chain pattern in the course of development did not correlate to the ATPase activity. 4. Antigenicity of the heavy chains in the embryonic myosin was the same as that of the adult heavy chains. However, antibodies to light chains were not detected in the antibodies to either the embryonic or adult myosins.