Regulation of Glyoxysomal Membrane Electron Transport

该研究的总体目的是确定在油籽萌发过程中，糖质体膜电子传递（GMET）系统的特征，该系统调节糖质体内脂肪代谢产生的NADH氧化。这种代谢过程是由乙氧基体内产生的NADH的氧化调节的。NADH被膜上由32 KDa蛋白（gm32）和二级转移蛋白(s)组成的GMET系统氧化。在油籽萌发过程中，脂代谢变得活跃的同时，乙氧化酶体获得膜电子传递活性。本项目的第一个目标是鉴定GMET的细胞质电子受体。将检查蛋白质的物理暴露。我们将确定GMET活性是否受到glyoxysomal membrane中不同蛋白质的出现或蛋白质修饰（如磷酸化）的调节。然后将确定gm32的氨基酸序列，以便与其他电子传递蛋白进行比较。这项工作是用从发芽的蓖麻胚乳中获得的乙氧化酶体进行的。这个项目涉及脂肪代谢，这直接关系到农业和人类健康。许多农业上重要的种子（玉米、向日葵、大豆、花生、棉花、蓖麻）都含有脂肪，并依靠脂肪代谢来发芽。特定的亚细胞细胞器，过氧化物酶体和乙醛酶体，参与脂肪的代谢。过氧化物酶体和乙氧化酶体由被膜包裹的酶（蛋白质）的浓缩溶液组成，脂肪由被膜包裹的酶代谢。当脂肪在过氧化物酶体或乙氧化酶体内代谢时，分子和能量（如电子）必须通过膜进出。因此，细胞膜必须含有调节细胞器内脂肪代谢的酶。本研究的具体目的是鉴定这些膜酶并确定它们是如何被调节的。膜运输的基本信息也可以用于理解人类的脂肪代谢。

The overall purpose of the investigation is to identify features of the glyoxysomal membrane electron transport (GMET) system which regulates oxidation of NADH generated by fat metabolism within glyoxysomes during germination of oil seeds. This metabolic process is regulated by the oxidation of the NADH generated within the glyoxysomes. NADH is oxidized by the GMET system comprised of a 32 KDa protein (gm32) and secondary transfer protein(s) in the membrane. During the germination of an oil seed, glyoxysomes acquire membrane electron transport activities at the same time that fat metabolism becomes active. The first objective of this project is to identify the cytoplasmic electron acceptors for GMET. The physical exposure of the proteins will be examined. We will determine if GMET activity is regulated by the appearance of different proteins in the glyoxysomal membrane or by modifications (e.g., phosphorylation) of proteins. The amino acid sequence of gm32 will then be determined, to allow comparison with other electron transport proteins. This work is being done with glyoxysomes obtained from the endosperm of germinating castor beans. %%% This project concerns fat metabolism, which is directly related to agriculture and to human health. Many agriculturally important seeds (corn, sunflower, soybean, peanut, cotton, castor bean) contain fat and depend on fat metabolism for germination. Specific subcellular organelles, peroxisomes and glyoxysomes, are involved in the metabolism of fats. Peroxisomes and glyoxysomes consist of a concentrated solution of enzymes (proteins) enclosed by a membrane and fat is metabolized by the enclosed enzymes. As fat is metabolized within a peroxisome or glyoxysome, molecules and energy (as electrons) must pass in and out, through the membrane. Thus the membrane must contain enzymes which regulate fat metabolism inside the organelle. The specific purpose of this investigation is to identify these membrane enzymes and to determine how they might be regulated. The basic information of membrane transport can then be applied to understanding fat metabolism in humans, as well.