Figure 1.
Targeting of the murine γ1 wild-type locus using a modified hMT vector with an inserted Ad splice donor site (Ad-5′ss). (A) Genomic organization of the murine IgG1 wild-type locus, the targeting vector, and the targeted Ad-hMT allele. The sγ1 probe used for Southern screening of homologous recombinant ES cell clones is represented as a black bar. Filled triangles indicate the primers used for screening of chimeric offspring. H, HindIII; E, EcoRI; Sc, ScaI; Amp, ampicillin resistance gene; TK, herpes simplex virus thymidine kinase gene; neo, neomycin resistance gene. (B) Detail of the γ1 wild-type and Ad-hMT targeted alleles. The genomic structure is compared with the hMT and s-hMT targeted loci (7). Sequences introduced by targeting vectors are shown in white: neo gene (neo), hMT promoter (hMT), artificial IhMT exon (IhMT); or in black: Ad splice donor site (Ad). The 114-bp fragment of wild-type sequence is represented as a hatched box. The phenotype of the mice is indicated with respect to transcription (transcription), splicing of the transcripts (processed transcripts), and class switch to IgG1 (class switch).

