cDNA sequence and gene expression of storage protein-2 - a juvenile hormone-suppressible hexamerin from the fall webworm, Hyphantria cunea Drury

We isolated and sequenced a cDNA clone corresponding to storage protein-2 ( SP-2) from the fall webworm, Hyphantria cunea. The cDNA for SP-2 (2572 bp) codes for a 737-residue protein with a predicted molecular mass of 88.5 kDa . The calculated isoelectric point is 7.6. Multiple alignment analysis of a mino acid sequence revealed that SP-2 is most similar to BJHSP2 (74.3% iden tity). According to both the phylogenetic analyses and criteria for amino a cid composition, SP-2 belongs to the subfamily of moderately methionine-ric h storage proteins (3.2% methionine, 11.8% aromatic amino acid). Topical ap plication of the JH analog, methoprene, after head ligation of larvae, supp ressed transcription of the SP-2 gene, indicating hormonal effects at the t ranscriptional level. The SP-2 transcript was detected by Northern blot ana lysis in Malpighian tubules, in addition to the fat body where it was most abundant. The local expression of SP-2 in Malpighian tubules suggests that it may have some function in that organ. (C) 2001 Elsevier Science Inc. All rights reserved.