Native myosin purified from the wild-type, N2, and a body-wall defective mutant, E675, of the nematode contains two myosins, each homogeneous for different heavy chains. These myosins can be resolved from one another on hydroxyapatite and, when cleavaged with CNBr, they yield different peptide-fragments. In E190, one of the homogeneous myosins is absent. e190
are alleles of the same gene, unc-54
. The myosin lacking in E190 is the same one affected in E675. This suggests that unc-54
is the structural gene for a myosin heavy chain. In order to determine the role of these different myosins, we plan to use antibodies to locate the myosins on thick filaments from body-wall muscle. Additionally, we are studying the patterns of synthesis and degradation of the two myosins in the wild-type and muscle-defective mutants in order to discover how the observed stoichiometry is maintained.