BOMBYX AND MANDUCA PROTHORACICOTROPIC HORMONES - AN IMMUNOLOGICAL TEST FOR RELATEDNESS

Prothoracicotropic hormone (PTTH) controls the synthesis of ecdysteroi ds (molting hormones) by the insect prothoracic gland and thereby play s a critical role in insect growth, molting, and metamorphosis. PTTH h as been purified, and cDNA clones obtained, from only one insect, the silkmoth Bombyx mori. Recently, a partial amino acid sequence was obta ined for a putative PTTH from the tobacco hornworm, Manduca sexta, and the data suggested an unexpected homology to a vertebrate retinoid bi nding protein rather than to the Bombyx PTTH. In this study, a monoclo nal antibody against the Bombyx PTTH was added to in vitro assays that assess the ability of partially purified Manduca PTTH to stimulate pr othoracic gland ecdysteroid and protein synthesis. The results indicat e that Bombyx and Manduca PTTHs are indeed members of the same protein family that have Likely diverged in the PTTH receptor-binding region. (C) 1996 Academic Press, Inc.