Human α-spectrin gene/^Aγ-globin transgenes. (A) A map of the erythrocyte α-spectrin promoter region. The minimal promoter (−794 to +1), untranslated exon 1′ (exon 1′), and intron 1′ (IVS1′), which is spliced out in 50% of α-spectrin transcripts, are shown. (B) A human α-spectrin (ASp) fragment containing the minimal α-spectrin promoter with or without downstream regions (ASp/^Aγ), exon 1′ + IVS 1 (ASpEx1IVS1/^Aγ), exon 1′ alone (ASpEx1/^Aγ), or IVS 1 alone (ASpIVS1/^Aγ), was fused to the human ^Aγ-globin gene to create the transgene constructs shown. One transgene, ASp promoter-exon 1-IVS1-splice mutant/^Aγ-globin-splice mutant (ASpEx1IVS1 splice mutant/^Aγ) was created with the conserved splice junction sequences of intron 1′ abolished.