Binding of myosin and its subfragment-1 with antibodies specific to the two heads of the myosin molecule.

It was shown by Miyanishi et al. [Miyanishi, T., Maita, T., Matsuda, G., and Tonomura, Y. (1982) J. Biochem. 91, 1845-1853] that the amino acid sequence around the reactive lysine residue is different between head B (Pi-burst head) and head A of the myosin molecule. Thus, we synthesized these two peptides, and prepared rabbit polyclonal antibodies against them. Each antibody bound strongly with both peptides. However, the binding of the antibodies with S-1 was inhibited by the peptide used for the antigen but unaffected by the non-antigen peptide, suggesting that only antibodies specific to each head can bind with S-1. Myosin was absorbed by either antibody A or B, which was immobilized on protein A in Staphylococcus aureus cells. However, half of S-1 was absorbed by each of the antibodies. The S-1 prepared showed about 0.5 mol of initial Pi-liberation per mol of S-1. The Pi-burst size of S-1 unbound to the immobilized anti-A antibody increased to almost 1 mol/mol S-1, while that of S-1 unbound to the anti-B antibody decreased to 0.15 mol/mol S-1. These results suggest the existence of two kinds of heads in the myosin molecule.