Relationship of hemolymph juvenile hormone-binding protein to lipophorin in Leucophaea maderae

Abstract

Monoclonal antibodies (MAb) specific for the hemolymph 220 kD juvenile hormone-binding protein (JHBP) of the cockroach, Leucophaea maderae, were used to further characterize the JHBP. Spleen cells, from mice immunized with semipurified hemolymph JHBP, were fused with myeloma cells to produce hybridomas secreting antibodies specific for the hemolymph 220 kD JHBP. Positive clones were recloned and rescreened by the same methods, resulting in the establishment of five cell lines producing IgG 2a anti-hemolymph JHBP antibodies. Using MAb against the 220 kD hemolymph JHBP, it was demonstrated by Western blot analysis that the 220 kD JHBPs present in both ovarian and egg case extracts have antigenic determinants similar to those of the hemolymph JHBP. In addition, both the 275 and 220 kD JHBPs, synthesized and secreted by fat body maintained in vitro, were detected by anti-hemolymph JHBP antibody, demonstrating that the two media proteins and the JHBP in the ovary share identical antigenic determinants. To determine if there is a relationship between hemolymph JHBP and lipophorin, hemolymph proteins were separated on potassium bromide gradients. Gradient analysis confirmed that the lipophorin complex bound JH and that the 220 kD JHBP is apolipophorin I (apolp I). The apolp I specific MAb did not cross-react with apoliphorin II (apolp II).