Nakato H, Takekoshi M, Togawa T, Izumi S, Tomino S
Department of Biology, Tokyo Metropolitan University, Japan.
Insect Biochem Mol Biol. 1997 Aug-Sep;27(8-9):701-9. doi: 10.1016/s0965-1748(97)00048-9.
A specific set of structural proteins termed larval cuticle proteins (LCPs) accumulates in integuments during larval development of the silkworm, Bombyx mori. Two major larval cuticle proteins, LCP17 and LCP22, were purified from the guanidine hydrochloride extract of the larval cuticle, and specific antibodies were raised against these proteins. Immunoblot analysis revealed that both LCPs are actively synthesized during larval intermolt stages, whereas the LCP17 epitope is also slightly but significantly detectable in pupal integuments. cDNA clones for LCPs were isolated by immunoscreening of the cDNA expression library constructed from larval epidermal mRNA. Predicted amino acid sequences of LCP17 and LCP22 are homologous to cuticle proteins from other insect species, including Manduca sexta, Drosophila melanogaster and Locusta migratoria. This fact suggests that these cuticle protein genes originated from a common ancestral gene and have been conserved during evolution. Northern blot hybridization demonstrated that the expression of LCP17 as well as LCP22 mRNA is controlled in a stage-specific manner in the epidermis of the final instar larvae, suggesting a common regulatory mechanism for transcription of these two intermolt genes.
一组特定的结构蛋白，即幼虫表皮蛋白（LCPs），在家蚕（Bombyx mori）幼虫发育过程中在体壁中积累。从幼虫表皮的盐酸胍提取物中纯化出两种主要的幼虫表皮蛋白LCP17和LCP22，并针对这些蛋白制备了特异性抗体。免疫印迹分析表明，这两种LCPs在幼虫龄间期均活跃合成，而LCP17表位在蛹体壁中也可轻微但显著地检测到。通过对由幼虫表皮mRNA构建的cDNA表达文库进行免疫筛选，分离出了LCPs的cDNA克隆。LCP17和LCP22的预测氨基酸序列与其他昆虫物种（包括烟草天蛾、黑腹果蝇和飞蝗）的表皮蛋白同源。这一事实表明，这些表皮蛋白基因起源于一个共同的祖先基因，并且在进化过程中得以保留。Northern印迹杂交表明，LCP17以及LCP22 mRNA的表达在末龄幼虫表皮中以阶段特异性方式受到调控，这表明这两个龄间期基因的转录存在共同的调控机制。
