Comparative studies on actins from various sources. Fragments of actins from Ascaris muscle cleaved at cysteinyl residues in comparison with those of other actins.

Pure actins were obtained from various animal muscles: Vertebrata (skeletal, smooth, and cardiac muscles), Prochordata (smooth muscle), Nematoda (obliquely striated muscle), and Mollusca (striated, smooth and obliquely striated muscles). These actins were all identical in apparent molecular weight on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. All actins treated with 2-nitro-5-thiocyanobenzoic acid yielded four major (about 33,000, 26,000, 24,000, and less than 10,000 daltons) and three minor (22,000, 17,000, and 10,000 daltons) bands in addition to intact actin on gel electrophoresis. The results suggest that all actins from various types of muscle have cysteinyl residues at similar positions on the primary structure.