Ligand blot analysis of juvenile hormone esterase binding proteins in Manduca sexta L

Biotinylated recombinant juvenile hormone esterase (JHE) was used for ligand blotting of proteins from fat body tissue and pericardial athrocytes of Manduca sexta. Proteins were separated by SDS-polyacrylamide gel electrophoresis or by two-dimensional electrophoresis. Eight putative JHE binding proteins were detected in fat body tissue and in pericardial athrocytes of both M. sexta and Heliothis virescens. The predominant bands were 29, 72, 75, 125 and 240kDa, with minor bands at 50, 80 and 205kDa. All putative JHE binding proteins were present from the second through to the fifth instar larvae of M. sexta. On wide-range isoelectric focusing, the 29kDa JHE binding protein separated into three species with isoelectric points of 6.5, 6.6 and 6.8. Biotinylated-JHE did not bind recombinant M. sexta-derived juvenile hormone binding protein. The mutant JHE with mutations K29R and K524R binds weakly to the JHE binding protein P29, relative to binding of wild-type JHE [Shanmugavelu et al., J. Biol. Chem., 275 (2000) 1802-1806]. A similar reduction in binding was not seen for the 29kDa binding protein identified here in pericardial athrocytes by ligand blot. This result is discussed.