Contains a 4.0kb fragment that includes the entire tra2 transcription unit and all the flanking sequences necessary for its expression, with a 7 nucleotide insertion within exon 4. Also contains mutations at highly conserved positions in both the donor and acceptor sites flanking the M1 intron, so that they differ from consensus sequences. The donor site is mutated from GUAAG to GGAUG, and the acceptor site is mutated from TCAAG to TCGAT.