Brennan M D, Warren T G, Mahowald A P
J Cell Biol. 1980 Nov;87(2 Pt 1):516-20. doi: 10.1083/jcb.87.2.516.
Translation of poly(A)-containing RNA from the female fat body of Drosophila melanogaster in a rabbit reticulocyte cell-free system results in the synthesis of previtellogenin polypeptides (PVs) having higher apparent molecular weights (46,000 and 45,000) than the forms seen after an in vivo pulse labeling. However, when this RNA is translated in the presence of EDTA-stripped microsomal membranes from the dog pancreas, vitellogenin precursors are produced that, upon SDS-polyacrylamide gel electrophoresis, comigrate with the in vivo forms (apparent molecular weights, 45,000 and 44,000). These processed forms are sequestered within the microsomal lumen, as evidenced by their insensitivity to trypsin digestion. Neither processing nor sequestration occur posttranslationally. In addition, a microsomal membrane fraction derived from Drosophila embryos is able to cotranslationally process the PVs as well as a murine pre-light chain IgG. These observations support a signal-mediated mode of secretion in Drosophila, and suggest that signal sequence recognition and signal peptidase activities are conserved even between mammalian and insect systems.
在兔网织红细胞无细胞体系中对黑腹果蝇雌性脂肪体中含多聚腺苷酸的RNA进行翻译，会合成前卵黄原蛋白多肽（PVs），其表观分子量（46,000和45,000）高于体内脉冲标记后所见的形式。然而，当这种RNA在存在经乙二胺四乙酸（EDTA）处理的狗胰腺微粒体膜的情况下进行翻译时，会产生卵黄原蛋白前体，经十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）分析，这些前体与体内形式（表观分子量45,000和44,000）迁移率相同。这些加工后的形式被隔离在微粒体腔内，这可通过它们对胰蛋白酶消化不敏感得到证明。加工和隔离都不会在翻译后发生。此外，源自果蝇胚胎的微粒体膜部分能够共翻译加工PVs以及小鼠前轻链IgG。这些观察结果支持果蝇中信号介导的分泌模式，并表明即使在哺乳动物和昆虫系统之间，信号序列识别和信号肽酶活性也是保守的。
