Cuticular proteins of the silkmoth Antheraea polyphemus

Abstract

Proteins from untanned pupal and adult abdominal cuticles, as well as pupal wing cuticle and adult wing scales from the oak silkmoth Antheraea polyphemus have been solubilized with denaturing solvents: SDS (2%), urea (8 M) and guanidine hydrochloride (6 M). Up to 50% of the proteins can be extracted by the procedure developed and all the solvents extract an approximately similar complement of proteins from the same cuticle. Both pupal and adult cuticles contain from 30 to 40 polypeptides separable on SDS-PAGE of which about ten in each case make up the major proportion. The major proteins fall in the molecular weight range of 15,000 to 45,000. SDS-PAGE and amino acid analyses indicate that (i) the protein composition of pupal and adult cuticles differ from one another (ii) the protein composition of cuticles, from different regions of the body e.g. wing or abdomen, are similar when derived from a particular stage (iii) proteins extracted from scales of adult wings represent a true reflection of the total adult wing cuticle and (iv) only minor differences exist between the proteins of segment and intersegment cuticle. Some of the major individual proteins have been isolated and analysis of amino acids, as well as the nature of digestion products obtained by limited proteolysis, indicate these to be unique. Immunological analyses, however, indicate some structural component to be common among some of the proteins because of good antibody cross reactivity.