Hp^tm1Alev

The targeted gene with its 5 coding exons has a high homology with a human gene that also has 5 coding exons. In humans, but not in mice, a second related gene exists where an in-frame duplication of exons 3 and 4 gives rise to a gene with 7 coding exons. To mimic this related gene in mice, murine coding sequence of exons 3 and 4 were placed upstream of exon 3 to create a "3-4-3" exon with no internal intronic sequence. The endogenous exon 3 was replaced with this 3-4-3 exon and a loxP-flanked neomycin selection cassette was inserted upstream. After crossing with Cre transgenic mice, the neomycin selection cassette was removed leaving some vector sequence within intron 2. After these events, the targeted locus has the following genomic structure: exon 1-intron 1-exon 2-intron 2 (with some vector sequence)-exon 3-exon 4-exon 3-intron 3-exon 4-intron 4-exon 5. Expression of the gene was confirmed by gel electrophoresis. (J:129061, J:134942)