Tanaka K, Mizuno S
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.
Insect Biochem Mol Biol. 2001 Apr 27;31(6-7):665-77. doi: 10.1016/s0965-1748(00)00173-9.
Low molecular mass protein components of fibroin, whose electrophoretic patterns before and after the reductive cleavage of disulfide bonds were similar to those of L-chain and P25 of Bombyx mori, were identified in fibroin samples of Bombyx mandarina, Dendrolimus spectabilis and Papilio xuthus but not of Antheraea yamamai. Fibroin of A. yamamai is suggested to form a dimer of H-chain. Full length cDNA sequences were cloned for the homologues of L-chain and P25 from B. mandarina, D. spectabilis and P. xuthus. The deduced sequences of L-chain and P25 of B. mandarina are almost identical to those of B. mori, each containing a single amino acid change. Homologues of L-chain and P25 of D. spectabilis and P. xuthus show about 50% overall identity, respectively, with those of B. mori, but essential structural features; i.e. the three Cys residues in an L-chain and the eight Cys residues and one of the potential N-glycosylation sites in P25, are conserved in both species. These results, together with the published results for Galleria mellonella, suggest that the three-components (H-chain, L-chain and P25) complex of fibroin is rather common among Lepidopteran silk-producing insects, in contrast to the H-H dimer type found in the saturnid silkworm.
在野蚕、黄褐天幕毛虫和柑橘凤蝶的丝心蛋白样品中鉴定出了丝心蛋白的低分子量蛋白质成分，其在二硫键还原裂解前后的电泳图谱与家蚕的轻链和P25相似，但在天蚕的丝心蛋白样品中未鉴定出。天蚕的丝心蛋白被认为形成重链二聚体。从野蚕、黄褐天幕毛虫和柑橘凤蝶中克隆了轻链和P25同源物的全长cDNA序列。野蚕轻链和P25的推导序列与家蚕的几乎相同，各自仅含一个氨基酸变化。黄褐天幕毛虫和柑橘凤蝶轻链和P25的同源物与家蚕的同源物分别显示约50%的总体同一性，但基本结构特征，即轻链中的三个半胱氨酸残基以及P25中的八个半胱氨酸残基和一个潜在的N-糖基化位点，在这两个物种中均保守。这些结果，连同已发表的大蜡螟的结果表明，与天蚕蛾中发现的重链-重链二聚体型相反，丝心蛋白的三组分（重链、轻链和P25）复合物在鳞翅目产丝昆虫中相当普遍。
