Contains 2 copies of a 700bp tra2 fragment in an antisense-sense inverted repeat arrangement. The fragment encompasses most of exons 6 and 7, and contains about half of the coding region and 297bp of the 3' UTR. The two copies are separated by 42bp of vector polylinker sequence and flanked by UASt sequences on one side and a polyadenylation signal and transcription terminator in the other.