Journal of Molecular Endocrinology

Mouse Pomc deletion strategies. (A) shows the normal 3 exon structure of Pomc. (B) Yaswen etal. (1999) used homologous recombination to replace a 9.5kb EcoRI fragment of the gene with a Pomc fragment in which the neomycin resistance gene had replaced all of exon 3. The translation product would therefore include the first 44 codons encoded on exon 2 followed by the neomycin resistance gene. Grey boxes represent the inserted homologous sequences. (C) Challis etal. (2004) used a more complex strategy in which a targeting vector included a PCR generated fragment targeting the 5' end of a 4.1kb fragment including a mutation of the authentic ATG start codon, and an insertion within the exon 3 boundaries of a tau-lacZ-PGK-neo cassette (white box), in which the PGK-neo sequences were flanked by loxP sites for possible future use in creating conditional knockouts. Grey boxes represent the inserted homologous sequences.