Figure 1.

The histone-Ul chimeric genes. A. The parent histone H2a-614 gene is shown (pH2a), with the 5′ and 3′ untranslated regions and the coding region indicated. The U5H and U50H gene have 226 nucleotides of 5′ flanking sequence and 5 or 50 nucleotides of the mouse Ulb coding region. The HU₁₁₇ and HU₁₅₆ genes have the Ul 3′ end starting at nucleotides 156 and 117 respectively, attached in the 3′ untranslated region of the histone H2a₆₁₄ gene. B. The UHU₁₅₆ and UHU₁₁₇ genes have both the Ul promoter and Ul 3′ end flanking the histone gene. The UHHU genes have the Ul 3′ end starting at nucleotide 156 or 117 of the coding region attached 25 nucleotides 3′ of the end of the U₅H gene. C. The sequences of the Ul-histone junctions in the U₅H, U₅₀H, HU₁₁₇, HU₁₅₆ genes are given. The coding region sequences of the Ul genes are underlined, as are the distal sequence element (DSE), proximal sequence element (PSE) of the Ul promoter, the ATG codon of the H2a-614 gene, and the 3′ end of the histone mRNA. The polylinker sequences are indicated. The restriction sites used are: AvaI; NarI.