Structure and expression of the silk adhesive protein Ser2 in Bombyx mori
Sericins are soluble silk components encoded in Bombyx mori by three genes, of which Ser1 and Ser3 have been characterized. The Ser1 and Ser3 proteins were shown to appear later in the last larval instar as the major sericins of cocoon silk. These proteins are, however, virtually absent in the highl...
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Veröffentlicht in: | Insect biochemistry and molecular biology 2009-12, Vol.39 (12), p.938-946 |
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Sprache: | eng |
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Zusammenfassung: | Sericins are soluble silk components encoded in
Bombyx mori by three genes, of which
Ser1 and
Ser3 have been characterized. The Ser1 and Ser3 proteins were shown to appear later in the last larval instar as the major sericins of cocoon silk. These proteins are, however, virtually absent in the highly adhesive silk spun prior to cocoon spinning, when the larvae construct a loose scaffold for cocoon attachment. We show here that the silk-gland lumen of the feeding last instar larvae contains two abundant adhesive proteins of 230 kDa and 120 kDa that were identified as products of the
Ser2 gene. We also describe the sequence, exon–intron structure, alternative splicing and deduced translation products of this gene in the Daizo p50 strain of
B. mori. Two mRNAs of 5.7 and 3.1 kb are generated by alternative splicing of the largest exon. The predicted mature proteins contain 1740 and 882 amino acid residues. The repetitive amino acid sequence encoded by exons 9a and 9b is apparently responsible for the adhesiveness of Ser2 products. It has a similar periodic arrangement of motifs containing lysine and proline as a highly adhesive protein of the mussel
Mytilus edulis. |
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ISSN: | 0965-1748 1879-0240 |
DOI: | 10.1016/j.ibmb.2009.11.005 |