FIGURE 1.

Generation of a conditional knock-out mouse line for Sepp1. To generate a conditional knock-out allele for Sepp1, a genomic fragment (bold black line) containing sequence from 5′-CTGAAGCAACAGCTAAAAGA-3′ to 5′-AACACTCCATGCAAACTACA-3′ of the Sepp1 gene was used for constructing the targeting vector. A, genomic structure of the wild-type (WT) Sepp1 gene, with its five exons shown in gray. The coding exons are gray and outlined in black. The second exon contains the start codon ATG. Sepp1 has 10 selenocysteines, each encoded by UGA in the mRNA. The first in-frame TGA is in the second exon. The remaining nine in-frame TGA codons are in exon 5. The 3′UTR of exon 5, where the two selenocysteine insertion sequence elements are located, is gray and is not outlined in black. B, loxP sites are represented by the open arrowheads in the targeting vector. The 5′ loxP site was inserted into the BglI site between exon 1 and exon 2. The 3′ loxP site and an FRT-flanked neo selection cassette were inserted into the SpeI site after exon 5. The arrows show the location of primers WS1004 and WS1005 used to assess the presence of the conditional allele. C, mating a heterozygous mouse with an Flp deleter mouse will delete the neo sequence between the two FRT sites (represented by the open hexagon), resulting in a clean Sepp1 conditional allele.