Transgenic construct used to study the 1A2 insulator (an endogenous insulator containing su(Hw)-binding sites which is found between the y gene and the ac-sc complex). Contains a fragment containing the y transcription unit and regulatory sequences. Nucleotides -146 to -70 relative to the y transcription start site have been deleted. The y wing and body enhancers are present upstream of this deletion and the y bristle enhancer is present downstream of the transcription start site. Downstream of the y transcription unit, there is a loxP cassette containing the 1A2 insulator, followed by a mini-w gene.