Diagrams of human CD34 genomic fragments used in transgenic mice.

The top 2 fragments were derived from PAC88L2, a 160-kb PAC clone extending 110 kb upstream of the transcription start site.19 The 3rd fragment representsMluI-digested PAC7H11, and the bottom 3 were derived from PAC54A19. Shown on the left are the restriction enzymes used to digest the PAC clones. Restriction sites that cut in the PAC vector (PvuI and MluI) are indicated by dotted lines. A unique MluI site is present in PAC88L2 at a position 31 kb upstream of the transcription start site, and a PvuI site is present in PAC54A19 25.7 kb 3′ of the polyadenylation site. PAC88L2 extends to position 24.1 kb 3′ of the polyadenylation site. Shown as short thick vertical lines are the 8 CD34 coding exons, which encompass 25 kb.8 The limits of the human CD34 sequence in PAC54A19 were determined by DNA sequencing. Shown on the right is the number of independent founder lines derived from each construct and the number that was observed to express human CD34 RNA and protein. Only the last construct failed to express human CD34.