The human endothelin-B receptor gene. Structural organization and chromosomal assignment.

The gene encoding the human endothelin-B receptor (hET-BR) has been isolated, and its structural organization and chromosomal assignment have been determined. Southern blot analysis demonstrated a single copy of the hET-BR gene in the human genome. The hET-BR gene spans 24 kilobases and consists of seven exons and six introns. The size range for exons is 109-2855 base pairs, although that for introns is 0.2-14.5 kilobases. Every intron occurs near the border of the putative transmembrane domain in the coding region. The major transcription initiation sites were mapped to the positions 258 and 229 base pairs upstream of the ATG initiation codon by primer extension and nuclease S1 protection experiments. The 5'-flanking region of the hET-BR gene lacks conventional TATA and CCAAT boxes but contains a sequence of potential Sp1 binding sites upstream of the transcription initiation sites. There are some canonical consensus sequences of cis-elements including GATA motif, acute phase reactant regulatory element, and E box. Using human-rodent somatic hybrid cell lines, the hET-BR gene was assigned to human chromosome 13. The present study will lead to a better understanding of the mechanism for the transcriptional regulation of the hET-BR gene and will give a clue as to how to search for possible genetic disorders of hET-BR.