The structure of a glycosylated protein hormone responsible for sex determination in the isopod, Armadillidium vulgare

Two glycoforms (AH(1) and AH(2)) of androgenic hormone, and its correspondi ng hormone precursor derived from HPLC-purified androgenic gland extract fr om the woodlouse Armadillidium vulgare were fully characterized by microseq uencing and mass spectrometry. The amino-acid sequences of the two glycofor ms were identical, they consist of two peptide chains, a and B, of 29 and 4 4 amino acids, respectively, with chain A carrying one N-glycosylated moiet y on Asn18. The two chains are linked by two disulfide bridges. Glycoforms were only differentiated by the size and heterogeneity of the glycan chain. The androgenic hormone precursor (16.5 kDa) was shown to contain the seque nce of chains A and B from the androgenic hormone, connected by a C-peptide (50 amino acids). These results were confirmed by matrix-assisted laser de sorption ionization-time of flight (MALDI-TOF) analysis performed on a sing le hypertrophied androgenic gland. When injected into young females, both g lycoforms of the androgenic hormone were able to override generic sex-deter mination. In invertebrates, there is no other example where sex-differentia tion is controlled by a protein hormone that is not synthesized by the gona ds but by a special gland. A functional comparison with two other hormones which are believed to play a role in sex determination, i.e. ecdysone in in sects and anti-Mullerian hormone in mammals, is presented. Work is in progr ess to clone and characterize the gene encoding androgenic hormone, moreove r special attention is devoted to its regulatory regions, putative targets for the Wolbachia action.