The targeting vector contains, from 5' to 3', a partial Chrna6 sequence within exon 6 up to and including the endogenous stop codon, an internal ribosome entry site 2 sequence (IRES2; allows translation initiation in the middle of an mRNA sequence), a FlpO recombinase gene (a codon-optimized FLPe gene modified for translation in mammalian cells and higher recombination efficiency in cells and in mice), a bovine growth hormone polyA sequence, an AttB site, a PGK/gb2 promoter-Neomycin resistance gene-PGK polyA cassette and an AttP site. (J:101977)