Nucleotide sequence analysis of mRNAs predicts that rat pituitary and gonadal gonadotropin-releasing hormone receptor proteins have identical primary structure.

In order to examine whether the paradoxical, extrapituitary ovarian and testicular gonadotropin-releasing hormone binding activity in rat was related to conventional pituitary GnRH receptor, the presence and nature of GnRH receptor gene transcripts were analysed by a reverse transcription-coupled polymerase chain reaction method. Different primer pairs designed to amplify regions of mRNA encompassing the complete open reading frame plus a large part of the 3'-untranslated region revealed the presence of GnRH receptor transcripts of strictly identical nucleotide sequence in both pituitary and gonads, predicting a unique primary structure for the receptor protein. In addition, restriction analysis of rat genomic DNA suggested that a single gene encodes the mRNA subspecies identified to date and demonstrated the presence of introns included within the highly conserved coding region. Although post-translational modifications of the GnRH-receptor may differ in the various tissues examined, these data at least clarify the nature and identity of gonadal GnRH receptors.