Isolation of rat GnRH receptor cDNA having different 5'-noncoding sequence.

A rat GnRH receptor cDNA was cloned with 1317 base pairs (bp) from a pituitary cDNA library. This clone had a full amino acid coding region, with 172 and 161 bp noncoding sequences in 5'- and 3'-flanking regions of the coding region, respectively. The nucleotide sequence of amino acid coding region was completely identical to that of previous report by Kaiser et al. (1992), but 5'-noncoding region was much longer than the previously reported one and its sequence was different. This 5'-noncoding region could be divided into two subregions on the basis of similarity between the two sequences. The 32 bp sequence flanking the coding region was completely identical to the previous report, but remaining 5'-end sequence almost totally lacked similarity. In the 3'-flanking region of coding region, 167 bp-long sequence was also newly identified. The new species of GnRH receptor mRNA found in the present study suggests that the presence of various mechanisms of GnRH receptor expression in the rat pituitary.