Polytene chromosomes normal.
Amino acid replacement: K284term.
Carries the nonsense mutation of its progenitor (Su(z)21) as well as a ~3.5kb deletion of the first two exons and a 4bp insertion (TTCT) at the site of the deletion. The putative TATA box is preserved 8bp upstream of the breakpoint, consistent with this allele being competent for transcription. (It is not known whether Su(z)21.b7 also carries the L120F mutation found in Su(z)21.)
2kb deletion from 0 to +2 on the molecular map.
2 kb deletion at 5' end of transcription unit