Properties and sequence of a female-specific, juvenile hormone-induced protein from locust hemolymph. 
In the fat body of Locusta migratoria, an RNA transcript of about 800 nucleotides has been detected that is specific to the adult female and dependent on induction by juvenile hormone (JH) or an analog.  The corresponding cDNA has been cloned (lambda 21) and a 718-base pair sequence determined.  It encodes a 196-amino acid polypeptide, including a signal peptide.  An NH2-terminal sequence has 24 out of 28 amino acids identical with those of a previously described 19K locust hemolymph protein, but the remainder of the sequence shows no similarity.  From adult female hemolymph, a 21-kDa protein, designated 21K protein, has been purified, with an NH2-terminal sequence exactly matching that deduced from clone lambda 21.  This 21K protein is found only in the adult female, is dependent on induction by JH, and is assumed to represent the product of the lambda 21 gene.  It shows no immunochemical cross-reaction with locust 19K protein, apolipophorin III, nor with vitellogenin (Vg).  Its isoelectric point is pH 5.4; it contains some carbohydrate.  21K protein is synthesized in adult female fat body, accumulates in hemolymph, and is taken up into the developing oocytes in parallel with Vg.  In locusts deprived of JH with precocene, production of 21K protein and of lambda 21-hybridizing transcripts is induced by the JH analog, methoprene, in parallel with Vg and its mRNA.  Because of its sex-, stage-, and JH-dependent regulation, coordinate with Vg, the 21K protein will be valuable for analysis of gene expression.