Comparative analysis of storage proteins of fall webworm (Hyphantria cunea, Drury)

Two kinds of storage protein (SP-1 and SP-2) were purified from the hemolymph of last instar larvae of Hyphantria cunea by ultracentrifugation, chromatofocusing, and ion-exchange chromatography. SP-1 and SP-2 each consist of six subunits and have the molecular mass of 79 KDa and 82.5 KDa, respectively. These showed different patterns of appearance in fat body and hemolymph, and different SDS-PAGE patterns in non-reducing gels. Their stability in citrate-phosphate or Tris-HCl buffers differs and their immunological characteristics indicates that these are different storage proteins. Comparison with storage proteins of other species with respect to amino acid composition and N-terminal sequence, indicates that SP-1 can be classified as a methionine-rich storage protein but SP-2 cannot be regarded as a classical arylphorin.