title: Determination of the site of disulfide linkage between heavy and light chains of silk fibroin produced by Bombyx mori.
abstract: The analysis of fibroin secretion-deficient 'naked-pupa' mutant silkworms has suggested that the disulfide linkage between heavy (H) and light (L) chains of fibroin, produced by the silkworm, Bombyx mori, is essential in its efficient large-scale secretion from the posterior silk gland cells. However, the site of disulfide-linkage between H- and L-chains has not been determined. In this study, cysteine residues involved in the single disulfide linkage between H- and L-chains were identified as the twentieth residue from the carboxyl terminus of H-chain (Cys-c20) and Cys-172 of L-chain by sequencing of genomic clones and peptide analysis. Furthermore, Cys-c4 (fourth residue from the carboxyl terminus) and Cys-c1 at the carboxyl terminus of H-chain were shown to form an intramolecular disulfide bond.
authors.affiliation: Laboratory of Molecular Biology, Department of Molecular and Cell Biology, Graduate School of Agricultural Science, Tohoku University, 1-1 Tsutsumidori-Amamiyamachi, Aoba-ku, Sendai 981-8555, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Tanaka
authors.forename: N
authors.initials: N
authors.lastname: Kajiyama
authors.forename: K
authors.initials: K
authors.lastname: Ishikura
authors.forename: S
authors.initials: S
authors.lastname: Waga
authors.forename: A
authors.initials: A
authors.lastname: Kikuchi
authors.forename: K
authors.initials: K
authors.lastname: Ohtomo
authors.forename: T
authors.initials: T
authors.lastname: Takagi
authors.forename: S
authors.initials: S
authors.lastname: Mizuno
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites; D012831:Bombyx / Q000235:genetics / Q000378:metabolism*; D003545:Cysteine / Q000737:chemistry*; D004220:Disulfides / Q000737:chemistry*; D005349:Fibroins / Q000737:chemistry*; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry; D014357:Trypsin
chemical_list: D004220:Disulfides; D010446:Peptide Fragments; D005349:Fibroins; D014357:Trypsin; D003545:Cysteine