FIG. 7.

Schematic representation of regulatory elements controlling ERVWE1 env gene expression. The URE is composed of a distal regulatory region (black line), truncated MaLR (hatched box), and a TSE region containing putative transcription factor AP-2, Sp-1, and GCMa binding sites. The ERVWE1 5′ LTR (white box) is composed of the U3, R, and U5 regions. The U3 region contains particular regulatory nucleotides (71, 210-211, 240, and 247) and the CAAT and TATA boxes. The CAP transcription initiation site (arrow) is located at the 5′ end of the R region. The forskolin (FK)-responsive domain of the U3 region corresponds to the basal promoter region (stippled line). The positive (+) or negative (−) involvement or the absence of an effect (n.e.) of regulatory domains and nucleotides on syncytin promoter activity in placental and other tissues is annotated below the schematic representation. The GCMa site in the TSE region and the Oct-1 site in the LTR were proven to interact with their relative transcription factors (9, 52).