Human transforming growth factor-β1 (hTGF-β1)　was produced in transgenic rice seeds. To boost its production yield and to extract it simply, it was expressed under the control of seed-specific promoters along with the simultaneous suppression of endogenous seed storage proteins　(SSPs)　through RNA interference (RNAi). When driven by the 26 kDa α-globulin endosperm-specific promoter, it accumulated up to the markedly high level of 452 μg/grain. However, exchange with other seed-specific promoters such as 18 kDa oleosin and AGPase promoters resulted in remarkable reduction to the levels of 62 and 48 μg/grain, respectively, even though endogenous SSPs were reduced to the similar level. These production levels were almost similar to those (42 and 108 μg/grain) produced by the glutelin GluB-1 endosperm-specific promoter and the maize ubiquitin constitutive promoter without reduction of SSPs, respectively. When extracted from these transgenic rice seeds with reduced SSPs with various buffers, it could be solubilized with denaturant solution, which was in remarkable contrast with those without depressed SSPs which required further supplementation of reducing agent for extraction. This difference was associated with the fact that it was mainly deposited to ER-derived structures though self-aggregation or interaction with remaining prolamin via intermolecular disulfide bonds.

中文翻译：

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通过高胚乳特异性表达以及同时抑制主要种子储存蛋白来提高重组蛋白的产量和提取效率

人类转化生长因子-β1 (hTGF-β1) 在转基因水稻种子中产生。为了提高其产量并简单地提取它，它在种子特异性启动子的控制下表达，同时通过 RNA 干扰 (RNAi) 抑制内源种子储存蛋白 (SSP)。当由 26 kDa α-球蛋白胚乳特异性启动子驱动时，它积累到 452 μg/粒的显着高水平。然而，与其他种子特异性启动子（如 18 kDa 油质蛋白和 AGPase 启动子）的交换分别导致显着降低至 62 和 48 μg/粒的水平，即使内源性 SSP 降低至相似水平。这些产量水平几乎与分别由谷蛋白 GluB-1 胚乳特异性启动子和玉米泛素组成型启动子产生的产量（42 和 108 微克/粒）相似，没有减少 SSP。当用各种缓冲液从这些SSPs降低的转基因水稻种子中提取时，可以用变性剂溶液溶解，这与那些没有SSPs降低的需要进一步补充还原剂进行提取的转基因水稻种子形成了鲜明的对比。这种差异与以下事实有关：它主要通过自聚集或通过分子间二硫键与剩余醇溶蛋白相互作用而沉积到 ER 衍生结构上。它可以用变性剂溶液溶解，这与那些没有降低SSPs的需要进一步补充还原剂进行提取的人形成了鲜明的对比。这种差异与以下事实有关，即它主要通过自聚集或通过分子间二硫键与剩余醇溶蛋白相互作用而沉积到 ER 衍生结构上。它可以用变性剂溶液溶解，这与那些没有降低SSPs的需要进一步补充还原剂进行提取的人形成了鲜明的对比。这种差异与以下事实有关：它主要通过自聚集或通过分子间二硫键与剩余醇溶蛋白相互作用而沉积到 ER 衍生结构上。