Characterization of a cysteine-rich protein specifically expressed in the silk gland of caddisfly Stenopsyche marmorata (Trichoptera; Stenopsychidae).
A novel protein, Smsp-72k, was found to be selectively expressed in the silk gland of aquatic larvae of the Stenopsychid caddisfly (Stenopsyche marmorata). The protein was characterized by an abundance of cysteine (13.97%) and charged residues (47.21%). Amino acids with hydroxyl side-chains accounted for an additional 10% of the Smsp-72k protein, with serine at 4.4% and threonine at 5.6%. A cysteine-rich repetitive sequence is common to many potential and known underwater adhesive/cement proteins and cell-cell adhesion molecules. We hypothesized that Smsp-72k is an adhesive/cement protein that increases the adhesiveness of the silk fiber of S. marmorata. The hydroxyl groups of Smsp-72k might form a link with the heavy chain fibroin of S. marmorata, removing the weak boundary-water layer and allowing the spreading of the silk protein onto the surface of the substratum during the process of adhesion.
Wang
Yujun
Y
Department of Applied Biology, Faculty of Textile Science and Technology, Shinshu University, Ueda, Japan. nakagak@giptc.shinshu-u.ac.jp
Wang
Hong
H
Zhao
Tianfu
T
Nakagaki
Masao
M
D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D003545:Cysteine; D018076:DNA, Complementary / Q000235:genetics; D005786:Gene Expression Regulation; D019476:Insect Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D007313:Insecta / Q000033:anatomy & histology* / Q000235:genetics / Q000378:metabolism*; D008853:Microscopy; D008969:Molecular Sequence Data; D047011:Silk / Q000378:metabolism*
D018076:DNA, Complementary; D019476:Insect Proteins; D047011:Silk; D003545:Cysteine