Nucleotide substitution: G3884A.
Amino acid replacement: W356term.
G15441747A
W357term | Act88F-PA
W356term
TGG to TGA
Heterozygotes rarely exhibit free myofibril fibres and if present they are cut, fragmented, torn and gapped. Indirect flight muscle fibres are normal in homozygotes and heterozygotes.
Heterozygotes are flightless with a normal wing posture.
Strongly induces heat shock proteins.
Actin III replaced by a truncated polypeptide of 42kD that is stable and capable of incorporation into myofibrils; actin II reduced in homozygotes. Myofibrils in indirect flight muscles of homozygotes severely deranged; sarcomere structure obliterated; indirect-flight-muscle nuclei enlarged. Skeins of morphologically normal but highly disorganized thick filaments present, but Z discs absent. Thin filaments scarce. Electron dense material of unknown origin seen in sections.
Wild-type flies transformed with cloned Act88F4 sequence produces both the 42kD and the heat-shock proteins.