Proteolytic fragmentation of Dictyostelium myosin and localization of the in vivo heavy chain phosphorylation site.

Dictyostelium myosin was associated into dimers and small oligomers at very low ionic strength, filamentous at intermediate ionic strength, and monomeric in solution conditions of high ionic strength. These different associations were probed by fragmenting myosin with chymotrypsin, trypsin, or V-8 protease. All three proteases digested monomeric myosin giving rise to multiple fragments with a wide range of molecular weights.