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. 2000 Mar 14;97(7):3444–3449. doi: 10.1073/pnas.050408497

Figure 1.

Figure 1

Targeting of the conditionally activated neu allele. (A) A schematic representation of the targeting construct and the genomic allele. The 2.5-kb 5′ arm of homology (SphI to Nar1) and the 8-kb 3′ arm of homology (KpnI to SalI) were used to direct the homologous recombination to the wild-type allele, illustrated by the dashed lines. Exon 1 of the endogenous allele was replaced by a loxP (triangle)-flanked PGK-neomycin-HSV poly(A) (Neo) cassette, followed by the neuNT cDNA and a simian virus 40 poly(A) (NeuNT). The loxP-flanked Neo NeuNT cDNA has replaced exon 1 contained within the Nar1/KpnI fragment. The size of the genomic HindIII (H3)-restricted fragment when detected by a probe 5′ to the site of homologous recombination also is depicted. Sp, SphI; N, Nar1; K, KpnI; Sl, SalI. (B) The recombinant allele containing the loxP-flanked Neo NeuNT cassette in place of exon 1 and the corresponding size of the HindIII restriction fragment detected by the external probe are shown. (C) A representative Southern blot of tail DNA from mice that are wild type (WT) and heterozygous for the knock-in (KI) allele.