FIG. 2.

Structure of the murine Pb99 gene and targeting construct. (a) Intron-exon structure of the nine exons (numbered 2 through 10) contained in the Pb99 genomic clones isolated. The unfilled boxes are exons that are not present in the Pb99.2 (exon 5) and Pb99.5 (exons 3 and 5) clones. Also shown is the Pb99-targeting construct (Pb99KO) described in the text. BamHI (B), EcoRI (R), and HindIII (H) sites are shown. (b) Southern blot of EcoRI-digested genomic DNA from +/+, +/−, and −/− mice probed with the 3′ KO probe, as described in Materials and Methods. Bands generated by the wild-type (WT; 20 kb) and targeted (KO; 16 kb) alleles are indicated.