SEQUENCE OF KAPPA-OPIOID RECEPTOR CDNA IN THE R1.1 THYMOMA CELL-LINE

To our knowledge, this is the first demonstration of kappa-opioid rece ptor mRNA in cells of the immune system. While the presence of opioid receptors on cells of the immune system has been controversial, cell-b inding analysis has indicated that the kappa-opioid receptor is expres sed by the immature T cell line R1.1. We have developed a reverse tran scriptase-polymerase chain reaction protocol to amplify the mRNA extra cted from R1.1 cells with primers derived from the cDNA sequence of th e mouse kappa-opioid receptor. Nucleotide sequences of the amplified p roducts were examined and two populations of cDNA were detected which differ in the 5' region upstream of the ATG start codon. Comparison of these sequences to the previously published kappa-opioid receptor cDN A sequence suggests the presence of an intron-exon junction in the 5' non-coding region.