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Expansion of the Superfamily of G-Protein-Coupled Receptors in Chordates
Department of Neuroscience, Uppsala University, Biomedical Center, 751 24 Uppsala, Sweden
Address for correspondence: Helgi B. Schiöth, Department of Neuroscience, Uppsala University, Biomedical Center, Box 593, 751 24 Uppsala, Sweden. Fax: +46-18-51-1540. helgis{at}bmc.uu.se
We have used sequence hidden Markov models to identify and classify all G-protein-coupled receptors (GPCRs) from 13 eukaryotic genomes. We found that the 5 main families found in mammals are present before the divergence of nematodes. We also found that several classes of GPCRs are not present within the vertebrate lineage, whereas they are present in several other taxa. The superfamily of GPCRs has a very dynamic gene repertoire, as evidenced by the several lineage-specific expansions of various families of GPCRs that we found. Further, the number of GPCRs has gradually increased with increased complexity of the organism.
Key Words: evolution • GPCRs • genome • hidden Markov models
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