Heterogeneity of juvenile hormone binding compounds in fat bodies of a cockroach

Fat bodies of adult vitellogenic or non-vitellogenic females and those of adult males contain 2 populations of saturable JH binding compounds. The respective Kd vales are 2-5 x 10(-9) M and 1-4 x 10(-8) M. Fat bodies of penultimate nymphs, hemolymph of any animal, and midgut epithelia contain one saturable JH binder with a Kd of 1-5 x 10(-8) M. Unlabeled JH I and III, as well as the JH analog ZR-515 compete effectively for the binding sites in these tissues. The 2 classes of hormone binders were separated by DEAE ion-exchange column chromatography. The very high affinity molecules of the adult fat bodies are presumably the specific JH receptors which may function in translocation of the hormone to the nucleus. The compound with relatively lower hormone affinity may be the JH hemolymph carrier which is also produced by the fat bodies and then exported.