Androgenic Gland Hormone

AGH is a sex hormone in crustaceans, which promotes sex differentiation into a functional male. The chemical structure of AGH was first determined in the terrestrial isopod Armadillidium vulgare, and is an insulin-like heterodimeric peptide with an Asn-linked glycan. Similarly to the mammalian insulin, AGH is produced as a single-chain precursor polypeptide consisting of a signal peptide, B-chain, C-peptide, and A-chain. The C-peptide portion is cleaved for maturation of the AGH molecule. The AGH gene is expressed only in a male-specific organ termed the androgenic gland (AG), and no expression is found in any tissue from females. Injection of AGH into young female A. vulgare induces masculization at a dose of 38pg/animal. In decapod crustaceans, an insulin-like molecule termed the insulin-like androgenic gland factor (IAG) exists in the AG. IAG gene silencing by RNAi reduces male secondary sex characteristics, and IAG is presumed to be an AGH in decapods.