Novel endothelin B receptor transcripts with the potential of generating anew receptor

Using RT-PCR and rapid amplification of 5' cDNA ends (5' RACE), we have clo ned three previously unrecognized endothelin B receptor (EDNRB) transcripts from a human melanoma cell line. Three distinct types of cDNAs (EDNRB Delt a 1, Delta 2 and Delta 3) were identified. EDNRB Delta 1 starts upstream of the published transcription start site of hEDNRB without splicing, whereas , EDNRB Delta 2 and EDNRB Delta 3 are alternatively spliced. EDNRB Delta 1 and EDNRB Delta 2 share the same transcription initiation site and are 560 bp upstream of the conventional hEDNRB, whereas that of EDNRB Delta 3 is 93 9 bp upstream from that described for the conventional hEDNRB. Interestingl y, many transcription factor motifs are detectable in the upstream regions of these transcription initiation sites. The predicted amino acid sequences reveal that EDNRB Delta 1 and EDNRB Delta 2 produce the same protein as th e conventional hEDNRB, but EDNRB Delta 3 would give rise to additional in-f rame 89- or 83-amino-acid residues at the N-terminus. EDNRB Delta 3 generat es the same amino acid sequence at the C terminus, but utilizes the polyade nylation signal within the open reading frame, resulting in a shorter 3'UTR . These transcripts are widely expressed in human tissues, but their expres sion patterns vary between different tissues. (C) 1999 Elsevier Science B.V . All rights reserved.