Sequence of the hexameric juvenile hormone-binding protein from the hemolymph of Locusta migratoria

The cDNA for the hexameric hemolymph juvenile hormone-binding protein (JRBP) from the migratory locust has been cloned and sequenced, Antiserum raised against purified JHBP was used to identify clones in an expression library. The 4.3-kilobase JHBP mRNA codes for 668 amino acids (74.4 kDa) and contains 2 kilobases of 3'-untranslated region, The derived amino acid sequence reveals that locust JHBP represents a new group within the hexamerin family of arthropod proteins. JHBP appears to be more closely related to arthropod hemocyanins, the believed ancestors of the family, than to the other known insect hexamerins. The mRNA shows a high (89%) bias to codons ending in G or C and the codons ending in A or T are clustered and concentrated toward the 5' end, suggesting a mosaic gene structure. The recombinant bacterially expressed protein bound [H-3]JH III with the same affinity as the protein from hemolymph. A truncated version of JHBP lacking 53 amino acids from the N terminus did not bind JH III. Hybridization analysis of fat body JHBP mRNA in locusts that had been treated with precocene and a JH analog did not give clear evidence for regulation by JH.