A fragment containing mutated Su(H) sequence has been reintroduced into the attP site present in Su(H)attP, resulting in a Su(H) coding region carrying the amino acid replacements L434A, L445A and L514A. Part of the first intron is duplicated compared to wild type, to avoid possible splicing defects due to the presence of the residual attR site. Intron 3 is absent. A single loxP site is present in the 3'UTR.
Su(H)LLF allele is larval to pupal lethal in homo- and hemizygosis, homozygous mutant larvae develop enlarged wing imaginal discs that contain no or sporadic sensory organ precursors.