Figure 2

Schematic of a general targeting vector used to introduce transgenes into the Hnf3α locus by homologous recombination. The 5' arm of homology contains Hnf3α genomic DNA that extends 3' of the Hnf3α transcriptional start-site (arrow). Coding sequences can be introduced into a unique Sal1 site that lies 5' to sequences containing an intron and polyadenylation signal for efficient RNA processing. A truncated Neo gene (ΔNeo) that lacks phosphotransferase activity provides the short arm of homology. Expression of ΔNeo is regulated by a Pgk promoter flanked by loxP elements. For electroporation into ES cells the targeting vector can be made linear by digesting with Sst1.