bioRxiv preprint doi: https://doi.org/10.1101/2020.05.11.088476; this version posted June 10, 2020. The copyright holder for this preprint (which was not certified by peer review) is the author/funder. All rights reserved. No reuse allowed without permission. 1 Arthropod IGF, Relaxin and Gonadulin, putative 2 orthologs of Drosophila insulin-like peptides 6, 7 and 3 8, likely originated from an ancient gene triplication 4 5 6 Jan A. Veenstra1, 7 8 1 INCIA UMR 5287 CNRS, University of Bordeaux, Bordeaux, Pessac, France 9 10 Corresponding Author: 11 Jan A. Veenstra1 12 INCIA UMR 5287 CNRS, Université de Bordeaux, allée Geoffroy St Hillaire, CS 50023, 33 615 13 Pessac Cedex, France 14 Email address:
[email protected] 15 16 Abstract 17 Background. Insects have several genes coding for insulin-like peptides and they have been 18 particularly well studied in Drosophila. Some of these hormones function as growth hormones 19 and are produced by the fat body and the brain. These act through a typical insulin receptor 20 tyrosine kinase. Two other Drosophila insulin-like hormones are either known or suspected to act 21 through a G-protein coupled receptor. Although insulin-related peptides are known from other 22 insect species, Drosophila insulin-like peptide 8, one that uses a G-protein coupled receptor, has 23 so far only been identified from Drosophila and other flies. However, its receptor is widespread 24 within arthropods and hence it should have orthologs. Such putative orthologs were recently 25 identified in decapods and have been called gonadulins.