Analyzing the pharmacological properties of Neopterygian Melanocortin-2 Receptor and Melanocortin-5
The objective of this study was to elucidate the phylogenetic differences between the Neopterygian fishes; bowfin (Amia calva), the gar (Lepisosteus oculatus), and a teleost representative species. The focus was to perform studies of the bowfin melanocortin receptors 2 and 5 and compare the data to the other species. Results of pharmacological studies showed that the MC2R obligate requirement for co-expression with MRAP1 was consistent with previous student on bony vertebrates, the lack of interaction with MRAP2 was consistent with previous studies on bony vertebrate MC2R orthologs. Both gar and bowfin MC2R showed similar dependence on the tryptophan residue in the HFRW motif of hACTH(1-24). However, the KKRRP motif in hACTH(1-24) played a less role in the activation of both bowfin and gar MC2R as compared to teleost MC2R orthologs. With respect to bowfin MC5R, the results were congruent with the results of gar MC5R in that neither had a preference for either MRAP1 or MRAP2. While these results confirmed the close phylogenetic relationship between bowfin and gar, this study was unable distinguish which of the neopterygian fishes was more closely related to the ancestral teleost.
