Functional binding of a vertebrate hormone, L-3,5,3'-triiodothyronine (T3), on insect follicle cell membranes.

A vertebrate hormone, L-3,5,3'-triiodothyronine (T3), induces volume reduction in the follicle cells of Locusta migratoria and Rhodnius prolixus. The effect of T3 on locust follicle cells is inhibited by ouabain and by antibodies raised against a membrane binding protein for juvenile hormone (JH). [125I]-T3 binds to membrane preparations of vitellogenic follicles in a specific and saturable fashion, with a KD in the low nanomolar range. T3 and JH III exhibited equivalent abilities to compete for the T3 binding site. These findings strongly suggest that T3 and JH act via the same receptor in follicle cells.