Bursicon
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The molecular structure of the hormone has been characterized rather recently. Bursicon is a 30 kDa neurohormone heterodimeric protein which is encoded by CG13419 gene and made of two cysteine knot subunits, Burs-α and Burs-β.[2] It is nondialyzable and loses its activity in alcohol, acetone, some proteases and trichloroacetate, renaturates after adding ammonium sulfate.[3]
Function
Bursicon plays a very important role in insect wing expansion during the last step of metamorphosis: maturation of the wing. At this time, the newly emerged adult removes dead cells of larval tissues. In Drosophila and Lucilia cuprina fly, the epidermis of wing is detached by extensive cell death apoptosis, at the time of wing spreading.
The cells that undergo death are removed from the wing cuticle and are absorbed into the thoracic cavity through wing veins. Subsequent wing maturation is disrupted if the process of cell death is inhibited or delayed somehow.
Bursicon is released just after eclosion and induces epidermis cell death. At the same time it hastens the tanning reaction, and hardens the newly expanded cuticle of the wing.[4]