The binding of juvenile hormone to membranes of follicle cells in the insect Rhodnius prolixus

3 H-labelled insect juvenile hormone, which has previously been shown to stimulate the Na,K-ATPase of membrane preparations of the follicle cells of the ovary of Rhodnius prolixus, exhibits saturable binding to microsomal preparations from the follicle cells of vitellogenic and previtellogenic follicles. No saturable binding is detectable in preparations from brain. Scatchard analysis shows that there is a greater density of binding sites on the membranes from vitellogenic, as opposed to previtellogenic, follicles. Sodium dodecyl sulfate – polyacrylamide gel electrophoresis of solubilized membrane preparations shows that the hormone binds to peptides in two regions of the gel, corresponding to 43 000 and 150 000 daltons. 3 HOuabain also binds to a peptide in the 150 000 region, as well as to the 100 000 region. Juvenile hormone thus may be binding directly to at least one of the constituent peptides of the Na,K-ATPase complex.