The transgenic construct contains the entire ubiquitin protein ligase E3A (Ube3a) gene; it is designed to have a loxp sites flanking exons 3-5. A single FRT site remains just downstream of exon 5 (a remnant of the FRT-flanked zeomycin resistance cassette that was removed by a FLP-expressing plasmid during the BAC recombineering). (J:244070)