sup-19 was identified as a weak recessive suppressor of the unc-15(e73) mutation, which results in a E342K charge change in UNC-15/paramyosin; the unc-15(e73) mutation results in myofibril disarray and disrupts interactions between UNC-15/paramyosin and MYO-3/MHCA; SUP-19 may specifically modify or interact with UNC-15/paramyosin before myofibril assembly, since the sup-19 mutation does not suppress mutations in unc-54, which encodes the major body-wall muscle myosin (MHCB); the molecular identity of sup-19 is not yet known.