Long terminal repeat nucleotide sequence and specific insertion of the gypsy transposon

We have determined the nucleotide sequences of the long terminal repeats of the transposable element gypsy from the cloned mutant alleles sc1, bx3, and bx34e. These mutations are suppressible by the suppressor of Hairy-wing, su(Hw). The long terminal repeats are 482 base pairs long and are highly conserved. In each case, gypsy is inserted into the sequence T-A-C-A-T-A and generates a duplication of the sequence T-A-C-A. This was verified by sequencing an empty site in the wild-type bx gene. Consideration of the sequence of the long terminal repeats and their surroundings limits the possible explanations for the mechanism of mutation by these gypsy insertions and for their suppression by su(Hw).