Structure and expression of mRNA for a pupal cuticle protein of the silkworm, Bombyx mori

Hiroshi Nakato, Mayumi Toriyama, Susumu Izumi, Shiro Tomino

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Electrophoretic and immunoblot analyses of proteins extracted from the salt-washed integuments of the silkworm Bombyx mori demonstrated that the pupal cuticle contains structural proteins distinct from those present in the larval cuticle. The cDNA clone encoding a pupal cuticle protein was isolated from the cDNA library constructed from epidermal mRNA of pharate pupae. Northern blot hybridization by use of a cDNA probe provided evidence that mRNA for the pupal cuticle protein accumulate in integument during larval-pupal transformation, though temporal rise of the mRNA level was also noticed at the stages of larval molting. Primary structure of the pupal cuticle protein was deduced from the nucleotide sequence of cDNA. The cloned mRNA sequence encodes a 27 kDa protein rich in alanine and proline, containing characteristic repeats of Ala-Pro-Ala-His-Gln-(Asp/Ser)-Trp-Asn sequence in the carboxyl-proximal domain. The sequence (Ile/Val)-(Leu/Ala)-(Asp/Glu)-Thr-Pro-Glu-Val-Ala-(Gln/Ala)-Ala-Arg-Ala-Ala-His-(Leu/Ile)-(Ala/Ser)-Ala-(Leu/His) occurs in three hydrophobic domains of the molecule.

Original languageEnglish (US)
Pages (from-to)667-678
Number of pages12
JournalInsect Biochemistry
Issue number7
StatePublished - 1990

Bibliographical note

Funding Information:
Acknowledgement--This work was supported in part by the Grant-in-Aid for Cooperative Research (Project number 62304009) from the Ministry of Education, Science and Culture, Japan.


  • Bombyx mori
  • Northern hybridization
  • cDNA cloning
  • cuticle protein
  • primary structure
  • stage-specific expression


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