Expression of spliced Dxz4 and promoter characterization. (a) Schematic map of the Dxz4 region representing 72.95 to 73.01 Mb of the mouse X chromosome (mm9). The map is inverted for simplicity and the distal direction toward Pls3 indicated. Open block arrows represent Dxz4 monomers. A downstream CGI is indicated. Immediately below is a map indicating location and type of repeat elements for the interval: LINE, long interspersed nuclear element; LTR, long terminal repeat; SINE, short interspersed nuclear element. Below that are the maps of two putative alternatively spliced transcripts based on expressed sequence tag evidence. (b) Confirmation of spliced transcripts by RT-PCR. Each of the seven panels is an image of an ethidium bromide-stained agarose gel showing RT-PCR results for PCR between the exons indicated above. To the left of each image is the predicted product size. Samples include water control (W) and RNA incubated with (+RT) and without (-RT) reverse transcriptase. (c) DNA sequence feature map of the 1.3-kb region immediately upstream of Dxz4 exon 1 (green). Repetitive elements are indicated above the corresponding colored boxes. Immediately below are the regions cloned upstream of a promoterless luciferase reporter gene: construct A (Con.A) and construct B (Con.B). (d) Luciferase activity measured in NIH/3T3 cell extracts 72 hours after transfection with the promoterless luciferase vector (pGL4.10) or the same vector containing inserts for construct A or B. Fold activation of luciferase is shown to the left. Data represent the mean and standard deviation of replicate experiments each performed in triplicate.