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Updated: Jun 23, 2026

Demonstration of the Sequence Alignment to Predict Across Species Susceptibility Tool for Rapid Assessment of Protein Conservation
Published on: February 10, 2023
Early duplications of opioid receptor and Peptide genes in vertebrate evolution
Dan Larhammar1, Susanne Dreborg, Tomas A Larsson
1Department of Neuroscience, Uppsala University, Uppsala, Sweden. Dan.Larhammar@neuro.uu.se
Abstract:
The opioid receptor family in mammals has four members called delta, kappa, mu, and NOP (the nociceptin/orphanin receptor). We show here that they arose from a common ancestral gene through quadruplication of a large chromosomal region, presumably in the two basal vertebrate tetraploidizations. The four opioid peptide precursor genes have a more complicated evolutionary history involving chromosomal rearrangements but nevertheless seem to have arisen in the same time period as the receptors. Thus the system of opioid peptides and receptors was already established approximately 450 Ma at the dawn of gnathostome evolution.
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