Inducation of antibody against actin from myxomycete plasmodium and its properties.

Plasmodium actin was highly purified by gel filtration of crude G-actin on Sephadex G-100 followed by ultracentrifugation after polymerization in the presence of 1 M urea and 1 mM ATP. Purified actin showed a single band in the sodium dodecyl sulfate gel electrophoretic pattern. Antibody against this purified actin was induced in rabbits. The antibody obtained was immunologically monospecific for plasmodium actin, judging from the following results. (1) The addition of the antibody to a plasmodium F-action solution increased the turbidity of the mixed solution, showing the formation of the antibody-action complex. (2) In immunodiffusion and immunoelectrophoresis, the antibody formed single preciptin lines with the purified actin preparation and with the crude actin extract from the acetone-dried powder of plasmodium. (3) The antibody inhibited polymerization of plasmodium G-actin. (4) Plasmodium F-actin filaments were decorated with antibody in electron micrographs. The antibody reacted not only with plasmodium F- and G-actin, but also reacted with sea urchin egg actin, but it did not react with actin from rabbit striated muscle.