FIG. 1.

Schematic representation of the human EDNRB locus. (A) Genomic organization of EDNRB, where the position of the HERV-E retroviral element, depicted as a rectangle flanked by two arrows, is shown with respect to the second exon of EDNRB. The location of the putative TATA box is indicated in the LTR (arrow) and the splice donor site is indicated (SD). The HERV-E element is approximately 6 kb in length and resides 52 kb upstream of the native promoter region, which is depicted as a circle. The transcription of four variant 5′ untranslated region isoforms appear to initiate within 1 kb downstream of the native promoter. The alternative transcripts possess identical coding regions starting with the ATG indicated in exon 2, with the exception of the isoform 1b, which contains an upstream ATG (in a dashed box) The small numbered arrows represent oligonucleotides used for real-time PCR. (B) Illustration of the alternative 5′ transcript forms.