| Abstract: |
Alternative splicing is a common mechanism used in eukaryotic gene regulation. Recently, we showed that the mouse mu opioid receptor gene undergoes extensive splicing. Fifteen MOR-1 variants were generated through differential splicing among the fourteen exons of the MOR-1 gene which span over 250kb. Here we report the identification of a novel splice variant, MOR-1R, of the mu opioid receptor gene from human brain. Human MOR-1R was isolated by using a 3'RACE and RT-PCR strategy. Sequence analysis of the MOR-1R showed that it contained the same coding exons 1, 2 and 3 as MOR-1, but a different fourth exon. The new fourth exon is predicted to encode 58 amino acids at the C-terminal of the MOR-1R. The deduced sequence is not significantly homologous to that of any of the known mouse variants. The new fourth exon has been mapped in the human MOR-1 gene through human genome database analysis. The splice site of the new exon is in agreement with consensus splice sequences. Expression of the MOR-1R mRNA was examined by Northern blot and RT-PCR analysis. Binding studies in CHO cells stably transfected with the MOR-1R/pcDNA3 construct indicated that MOR-1R encodes a mu opioid receptor. |
