Hprt1^{tm338a(Ple284-icre/ERT2)Ems}

The transgene consists of a bEMS122 human bacterial artificial chromosome (BAC) retrofitted to contain a human HPRT complementary sequence (containing exon 1, intron 1, exon 2 and part of intron 2), a mouse 3' Hprt homology arm, an I-Sce linearization cut site, and a mouse 5' Hprt homology arm; all inserted into the sacB gene in the BAC vector. Next, an iCre/ERT2 fusion gene, an intron, an SV40 early polyA signal and a 48-bp full Frt (Ffrt) site-flanked kanamycin resistance (Kan) cassette were inserted directly at the ATG of the human NR2E1 locus. Transient transfection with a FLP recombinase plasmid removed the Kan cassette before the modified BAC was used for targeting as a single copy "knock-in" into the upstream region of the Hprt locus. (J:204202)