Fig. 2. Generation of Fez-deficient mice. (A) Schematic diagram of the Fez gene locus (wild-type allele), targeting vector and targeted allele. Exons containing the zinc-finger domains are indicated by gray boxes. The targeting vector contains a phosphoglycerate kinase I promoter-linked neomycin-resistance gene (PGK-NEO) in place of part of the coding region (amino acids 1-350), and a thymidine kinase gene (TK) at the end of the 3' arm. E, EcoRI; H, HindIII; K, KpnI; X, XbaI; B, BamHI. (B) Southern blot analysis of the targeted ES clones. EcoRI- and BamHI-digested DNA from wild-type ES clones (+/+) and targeted clones (+/–) was hybridized with the probe shown in A (HindIII-KpnI fragment). The wild-type and targeted alleles showed 5.5- and 3.5-kb bands, respectively.