Moulting hormone action is mediated mainly by the intracellular ecdysteroid
receptor, a member of the nuclear receptor family. The receptor is compose
d of several functional domains, responsible for transactivation, DNA bindi
ng, ligand binding, dimerization with other nuclear receptors and interacti
on with additional proteins e.g. comodulators. Receptor function is modulat
ed by intramolecular interactions between receptor domains and intermolecul
ar allosteric effects of various dimerization partners. Tissue-, developmen
tal stage- and gene-specific diversification of the hormonal signal is nece
ssary to coordinate the activity of more than 100 ecdysteroid dependent gen
es. This is enabled by tissue specific hormone metabolism, posttranslationa
l modification of the receptor protein, receptor isoforms, various dimeriza
tion partners and interaction with different comodulators.