CHARACTERIZATION OF THE TRANSCRIPTION START SITE OF THE ACTH RECEPTORGENE - PRESENCE OF AN INTRONIC SEQUENCE IN THE 5'-FLANKING REGION

Corticotropin (ACTH) regulates glucocorticoid production through speci fic receptors on the adrenal cortex. Analysis of the ACTH receptor mRN A in human adrenal has revealed the presence of five transcripts rangi ng from 1.8 to 11 kilobases (kb). Characterization of the 5'-untransla ted regions (UTRs) of the ACTH receptor mRNA demonstrated the presence of one major initiation site of transcription 177 bp away from the AT G codon. Analysis of this 5' sequence showed a perfect alignment with the previously described genomic sequence until position -128 bp from the ATG. The upstream 49-bp sequence was divergent, suggesting the occ urrence of a splicing and indicating the presence of an intronic seque nce in the UTRs, as well as the presence of an upstream exon containin g this 49-bp sequence and located at least 1.8 kb away from the exon e ncoding the protein.