A hydrophobic peptide (VAP-peptide) of the silkworm, Bombyx mori: structure, expression and an enhancing function of diapause hormone activity.
We have recently identified a unique lipophilic peptide (VAP-peptide) with diapause egg inducing activity in the silkworm, Bombyx mori (Imai et al., 1996). The cloning and sequencing of cDNA encoding VAP-peptide have demonstrated that the deduced amino acid sequence consisted of 84 amino acid residues, from which the mature VAP-peptide of 68 amino acid residues was released by cleaving a signal sequence. Searches of the GenBank data base revealed no significant sequence similarity to other proteins including diapause hormone (DH). VAP-peptide gene was selectively expressed just before and at adult eclosion in the head and the thorax not in the abdomen. By a Western blot analysis, VAP-peptide was also localized in the head and the thorax of adults. The purified recombinant VAP-peptide could not induce diapause eggs even when injected at a high dose of 10 nmol/pupa. Whereas, injection of a mixture of VAP-peptide and DH clearly decreased a half-maximum dose (ED50 value) and a threshold dose (TD value) of DH, and these values decreased according to increasing molar ratios of VAP-peptide to DH. Thus, the VAP-peptide is concluded to be an endogenous protein acting as a potent enhancer of DH activity through interaction with DH.
Shiomi
K
K
Graduate School of Bioagricultural Sciences, Nagoya University, Japan.
Sato
Y
Y
Imai
K
K
Yamashita
O
O
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D012831:Bombyx / Q000737:chemistry / Q000235:genetics / Q000254:growth & development*; D018076:DNA, Complementary / Q000737:chemistry; D047108:Embryonic Development; D018507:Gene Expression Regulation, Developmental; D007301:Insect Hormones / Q000235:genetics*; D008297:Male; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000235:genetics* / Q000302:isolation & purification
D018076:DNA, Complementary; D007301:Insect Hormones; D010446:Peptide Fragments; C115047:VAP peptide