FIG. 1.

Schematic representation of the ovine β-LG gene, the expression vector pBJ41, and the transgene constructs pBJ41-A1H and pBJ41-A1L. Exons of the β-LG gene and the human IgG genes are represented by shaded boxes and filled boxes, respectively. Exons encoding the heavy chain constant region are marked as 1, H, 2, and 3; the exon encoding the light chain constant region is marked as Cκ. The inserted variable regions (Vγ and Vκ) isolated from the A1 mouse hybridoma cell line are represented as hatched boxes. The mammary gland-specific expression vector pBJ41 contains sequences from the first and fifth exons (17 and 8 bp, respectively) and the entire sixth and seventh exons of the β-LG gene. A linker carrying a singular EcoRV site was inserted in between the two PvuII sites in exons 1 and 5. a, b, and c, β-LG translational initiation site, stop codon, and polyadenylation signal, respectively; d and e, IgG translational start and stop codons, respectively. The A1 heavy chain coding region was inserted as a blunt-ended NcoI-EagI fragment into the singular EcoRV site of pBJ41. The A1 light chain coding region was inserted as a blunt-ended NcoI-EcoRI fragment into the same site.