Bursicon is a heterodimeric neuropeptide responsible for cuticle tanning (melanization and sclerotization) and wing expansion in insects.Functional bursicon consists of two cystine knot subunits, referred to as bursicon (burs) and partner of bursicon (pburs), which acts through a specific G protein-coupled receptor (GPCR) DLGR2, encoded by the rickets gene in Drosophila.