Final heterodimeric neurohormone released at the end of the molting cycle, involved in the sclerotization (tanning) of the insect cuticle, melanization and wing spreading. Heterodimer specifically activates the G protein-coupled receptor rk. Heterodimer of Burs and Pburs. Expressed in one to two pairs of neurons in each of the thoracic and abdominal neuromeres of the larval CNS. Coexpressed with CCAP in most CCAP-specific neurons. Coexpressed with Pburs in four bilateral neurons in thoracic and abdominal neuromeres of the ventral nervous system. Expression is low in larval stages and increases before ecdysis; consistent with role in postecdysial cuticle changes.