AIP3P AND REGULATING ACTIN ORGANIZATION

AIP3P 和调节肌动蛋白组织

• 批准号: 6386716
• 负责人: DAVID C AMBERG
• 金额: $ 19.89万
• 依托单位: UPSTATE MEDICAL UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-05-01 至 2003-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6386716
• 关键词: Saccharomyces cerevisiae; actins; calmodulin; cell cycle; cellular polarity; cytoskeletal proteins; immunoelectron microscopy; kinesin; protein localization; yeast two hybrid system

The proposed experiments are aimed at understanding how the actin cytoskeleton becomes polarized, thereby causing growth of yeast to be polarized (i.e., direct to the bud). Late in the G1 phase of the cell cycle, the actin cytoskeleton becomes oriented: actin cables align and point to the incipient bud site, and end in patches of actin at the cell cortex (cortical patches) where the bud will emerge. The process of bud site selection and actin cytoskeleton polarization requires several proteins. Central to the mechanism that polarizes actin cables and patches is the small G-protein Cdc42. It is thought that activation of Cdc42 by the Cdc28 CDK causes it to orient actin. How this is achieved is not known. Among the several proteins that have been implicated in this process is Aip3, which Amberg identified as an actin-interacting protein with the 2-hybrid technique. He believes that Aip3 is involved in actin polarization for two reasons. First, deletion of AIP3 disrupts actin polarization. Mutants can initiate bud formation, but cannot maintain actin polarity, resulting in depolarized growth, inefficient targeting of secretory vesicles to the bud site, enlarged, disorganized cells, poor septum formation, random bud-site selection in diploids, defective nuclear segregation in mitosis. Second, Aip3 localizes to sites that overlap cortical actin, suggesting that it is associated with polarized actin and could play a role in the process. The idea that Aip3 plays a role in directing actin assembly at the bud site is supported by the observation that Aip3 localizes to the bud neck well before actin cortical patches assemble there. However, Aip3 is not absolutely required for actin assembly at the bud site, nor for septin assembly at the bud site, since both of these processes occur (but with less efficiency and fidelity) in Aip3 mutants.

提出的实验旨在了解肌动蛋白如何 细胞骨架变化，从而导致酵母的生长 极化（即直接直达芽）。 在细胞的G1阶段后期 循环，肌动蛋白的细胞骨架成为方向：肌动蛋白电缆对齐和 指向初期的芽位，并以细胞的肌动蛋白斑点结尾 皮质（皮质斑块），芽将出现。 芽的过程 位点选择和肌动蛋白细胞骨架极化需要几个 蛋白质。 使肌动蛋白电缆两极的机制和 补丁是小的G蛋白Cdc42。 人们认为激活 CDC28 CDK的Cdc42导致其向上肌动蛋白。 如何实现 不知道。 在涉及的几种蛋白质中 此过程是AIP3，Amberg将其识别为肌动蛋白相互作用 蛋白质与2杂交技术。 他认为AIP3参与了 在肌动蛋白极化中有两个原因。首先，删除AIP3破坏 肌动蛋白极化。 突变体可以发起芽形成，但不能 保持肌动蛋白极性，导致去极化的生长，效率低下 将分泌囊泡靶向芽位，扩大，混乱 细胞，隔膜形成不良，二倍体中随机芽位选择， 有丝分裂中有缺陷的核分离。 第二，AIP3本地化为 与皮质肌动蛋白重叠的位点，表明它与 两极分化的肌动蛋白可以在此过程中发挥作用。 这个想法 AIP3在指挥肌动蛋白组件的芽位置为 由AIP3定位在芽脖子井的观察结果支持 在肌动蛋白皮质斑块组装之前。 但是，AIP3不是 在Bud网站上绝对需要肌动蛋白组件，也不需要Septin 由于这两个过程都会发生，因此在芽站点的组装（但是 AIP3突变体中的效率和保真度较低。