Mobilization of Triacylglycerol Stores in Insects

描述：(申请人提供)：与脊椎动物不同， 脂肪酸以游离脂肪酸的形式被动员，大量的昆虫， 以AN-1，2-二酰基甘油(DG)的形式动员脂肪酸。甘油三酯动员 商店需要甘油三酯脂肪酶的作用，它的活性是荷尔蒙的 受监管的。脂肪酶底物(Tg)存在于较大的细胞内。 脂滴，由被络合物包围的TG核心组成 磷脂和蛋白质的表层。另一方面，甘油三酯脂肪酶 定位于脂解未受刺激的脂肪体细胞的胞浆中。 脂解作用涉及脂肪酶与脂质表面的相互作用。 水滴。已知，脂解作用的激活促进了 细胞内钙离子浓度与AMP依赖蛋白的激活 激酶(A-Kinase)的基本机制是如何 磷酸化-去磷酸化反应调节脂肪分解的速度 未知。此外，人们对这一事件的相关性和性质知之甚少 影响脂滴的结构和成分变化 脂肪分解是由荷尔蒙激活的。这些变化最终必须影响到 脂肪酶与脂质底物及其伴生物的相互作用 脂解的激活。DG从脂滴移动到质膜 通过一种未被刻画的机制。看来，在TG转换之后 在脂滴表面进入DG，DG将转移到 胞质载体，这反过来又将靶向DG在整个 质膜。这个项目的总体目标是建立 通过确定促进脂肪分解的因素来调节脂肪分解的机制 甘油三酯-脂肪酶与底物、脂滴和TO的相互作用 明确DG的细胞内转运机制。显然，这一解释 在昆虫生物化学和生物化学中具有重要意义 生理学。这些研究将提供有关 昆虫的脂肪分解过程，这一知识也可能有助于 脊椎动物脂肪代谢和运输的广阔领域。

DESCRIPTION: (provided by the applicant): Unlike vertebrates, where the stored fatty acids are mobilized as free fatty acids, a great number of insects, mobilizes fatty acids as an-1, 2-diacylglycerol (DG). The mobilization of TG stores requires the action of a TG-lipase, whose activity is hormonally regulated. The substrate of the lipase (TG) is found in large intracellular lipid droplets, which are constituted by a core of TG surrounded by a complex surface layer of phospholipids and proteins. On the other hand, the TG-lipase localizes in the cytosol of lipolytically unstimulated fat body cells. Lipolysis involves the interaction of the lipase with the surface of the lipid droplet. It is known that activation of lipolysis promotes both an increase of intracellular calcium concentration and activation of amp-dependent protein kinase (A-kinase) but the basic mechanisms involved in how phosphorylation-dephosphorylation reactions modulate the rate of lipolysis is unknown. Moreover, little is known about the relevance and nature of the structural and compositional changes that affect the lipid droplet when lipolysis is hormonally activated. These changes must ultimately affect the interaction of the lipase with the lipid substrate and the concomitant activation of lipolysis. DG moves from the lipid droplet to the plasma membrane by an uncharacterized mechanism. It appears that after the conversion of TG into DG on the surface of the lipid droplets, DG would be transferred to a cytosolic carrier, which in turn would target the delivery of DG across the plasma membrane. The overall goals of this project are to establish the mechanisms regulating lipolysis by determining the factors that promotes the interaction between TG-lipase and its substrate, the lipid droplet and to define the mechanism of intracellular transport of DG. Clearly the elucidation of these mechanisms is of fundamental importance in insect biochemistry and physiology. These studies will provide comprehensive information on the lipolytic process in insects and this knowledge could also contribute to the broad field of lipid metabolism and transport in vertebrates.