FIG. 7.

Construction of transgenes encoding β^WT and β^RT β-globin mRNAs. (A) Transgene structures. The β^WT and β^RT transgenes comprise the full-length hβ-globin gene, including native promoter (P) and 3′ enhancer (E) elements, linked in their native orientation to a β μLCR (LCR) (63). The two transgenes are identical except for two tandem mutations (asterisks) in exon 3 of the β^RT transgene (54). Tick marks indicate the positions of the native translation initiation and termination codons. (B) Structures of β^WT and β^RT mRNAs. The 5′-cap (●), poly(A) tail (A_n), and native translation initiation and termination codons (tick marks) are indicated. Asterisks denote the positions of tandem mutations in the β^RT mRNA. The region of each mRNA that is actively translated is indicated by an arrow.