Generation of the IL-15Rα^ext/IL-2Rα^int KI mice. (A) Schematics showing the gene structure of IL-15Rα, targeting construct, targeted allele after homologous recombination, and the KI allele after deletion of the neo cassette by Cre recombinase. ■ represents exons, and the hatched box in exon 6 indicates the insertion of the coding sequence of IL-2Rα intracellular domain. (B) ES cells containing the KI allele. Genomic DNA from the ES cells was digested with HpaI and Southern-blotted with probe A indicated in panel A. (C) After homologous recombination, an XhoI site was inserted 5′ to the first LoxP site. Southern blotting with probe B after XhoI digestion exhibited a band of 14.6 kb in the WT allele, a 4.4-kb band in the KI allele after homologous recombination, and a 2.5-kb band in the KI allele after excision of the neo cassette by Cre recombinase. (D) Schematic of partial structure of IL-15Rα cDNA. The numbers represent the corresponding exon numbers in the genome. 6a and 6b are from exon 6 but separated by the insertion, which is indicated by a hatched box. The location of forward (Fwd) and reverse (Rev) primers used to amplify the IL-15Rα cDNA is shown. (E). Total RNA was isolated from total splenocytes, reverse-transcribed, and amplified with primers as in panel D.