INSECT STORAGE PROTEINS

昆虫已经进化出一种储存氨基酸的系统， 在幼虫最后取食阶段，由食物蛋白质产生的酸 被用来合成大量的一些定义明确的蛋白质， 贮藏蛋白 贮藏蛋白是六聚体，含有一个或多个 亚单位的类型。 在Manduca sexta中，研究的主题是 在应用中，存在三种主要的储存蛋白（SP）; SP-1或SP-2。 arylphorin，富含芳香族氨基酸的蛋白质; SP-2，富含 蛋氨酸;和SP-3，一种尚未表征的贮藏蛋白。 期间 在最后的幼虫阶段，这些蛋白质积累到非常高的水平， 血液和它们的mRNA代表脂肪体中的主要种类， 合成。 在幼虫生命结束时，SP-2和SP-3被带回到 脂肪体和包装的蛋白质颗粒，而SP-1仍然在 血 SP-1在两性中同样存在，而SP-2和SP-3在两性中存在。 女性血液中的浓度要高得多，在血液中出现的时间更早 末龄雌虫的死亡率高于雄虫。 这些蛋白质都没有 存在于成虫的血淋巴中。 储存蛋白是两个基本的模型， 细胞生物学中的问题，即，1）激素和发育是如何 它们的基因表达受到控制; 2）储存蛋白是如何 被脂肪体吸收，这个系统如何区分 两类贮藏蛋白 我们建议使用贮藏蛋白质来 在烟草天蛾Manduca模型系统中研究这些问题 （1）确定一个人的年龄; SP-2和SP-3的蛋白质（cDNA）和基因序列; 2）调查 贮藏蛋白基因中潜在的顺式调控元件; 3） 识别的交易因素的分离和表征 贮藏蛋白基因中的顺式调控元件; 4）表征 脂肪体对蛋白质的吸收。

Insects have evolved a system for storage of amino acids in which amino acids derived from dietary proteins during the last feeding larval stage are used to synthesize large amounts of a few well-defined proteins, called storage proteins. Storage proteins are hexamers, containing one or more types of subunits. In Manduca sexta, the subject of study in this application, there are three major storage proteins (SP); SP-1 or arylphorin, a protein rich in aromatic amino acids; SP-2, a protein rich in methionine; and SP-3, an as yet uncharacterized storage protein. During the last larval stadium, these proteins accumulate to very high levels in the blood and their mRNAs represent major species in the fat body, the site of synthesis. At the end of larval life SP-2 and SP-3 are taken back into the fat body and packaged as protein granules, while SP-1 remains in the blood. SP-1 is found equally in both sexes, whereas SP-2 and SP-3 occur in much higher concentrations in female blood and appear earlier in the blood of last instar female larvae than in male larvae. None of these proteins are found in adult hemolymph. THe storage proteins serve as important models for two fundamental questions in cell biology, viz, 1) how is the hormonal and developmental expression of their genes controlled; and 2) how are the storage proteins taken up by the fat body, and how does this system discriminate between the two classes of storage proteins? We propose to use the storage proteins to investigate these questions in a model system, the tobacco hornworm Manduca sexta, through pursuit of the following specific aims: 1) Determination of the protein (cDNA) and gene sequences for sp-2 and sp-3; 2) Investigation of potential cis-regulatory elements in the storage protein genes; 3) Isolation and characterization of transacting factors which recognize cis-regulatory elements in the storage protein genes; 4) Characterization of storage protein uptake up the fat body.