ELASTIN/LAMININ RECEPTOR

弹性蛋白/层粘连蛋白受体

基本信息

批准号：
2220207
负责人：
ROBERT P. MECHAM
金额：
$ 23.82万
依托单位：
WASHINGTON UNIVERSITY
依托单位国家：
美国
项目类别：
财政年份：
1989
资助国家：
美国
起止时间：
1989-07-01 至 1999-05-31
项目状态：
已结题

项目摘要

During the current funding period, we have continued our studies of EBP67, a 67 kDa elastin-binding protein found on elastin-producing cells. Unlike signaling or adhesion receptors, EBP67 participates in the assembly of the elastic fiber by mediating the transfer of tropoelastin to assembly sites on microfibrils. Based on many common features with intracellular chaperones, we propose that EBP67 functions as a molecular chaperone for tropoelastin. Like many chaperones, EBP67 preferentially binds to hydrophobic sequences, has evolved a mechanism for selected release of protein ligand, and participates in oligomeric assembly. EBP67 also exhibits many properties that suggest it might play an imperant role in the intracellular management of tropoelastin secretion, such as intracellular colocalization with tropoelastin and interactions with cytoskeletal components that act as motors for moving EBP67-tropoelastin complexes. We have also found that a 61 kDa protein that purifies with EBP67 is TCP-1, itself a major component of cytoplasmic chaperones. The possibility that EBP67 may be a chaperone for a secreted protein is an important new extension of the chaperone paradigm. Another important observation made during the current funding period was that the integrin alpha-v-beta3 binds to the microfibrillar protein fibrillin. This raises the interesting possibility that alpha-v-beta-3 is an integral component of elastic fiber assembly sites on the plasma membrane. These assembly sites morphologically resemble focal contacts as characterized by dense areas of membrane with an accumulation of cytoskeletal elements on the cytoplasmic side. Given the propensity of alpha-v-beta3 to associate into focal contacts and to interact with the cytoskeleton, we hypothesize that this integrin plays an important role in defining assembly sites through its bridging interactions between the intracellular cytoskeleton and fibrillin on the plasma membrane. Our future objectives are to continue to characterize EBP67 and its accessory proteins and to explore EBP67's possible function as a molecular chaperone. We will also examine a possible role for alpha-v-beta3 integrin in elastic fiber assembly. Finally, we wish to better define the elastic fiber assembly site on the cell surface. Our specific aims are: l) To further characterize EBP67 and its accessory proteins; 2) To characterize the structural motifs recognized by EBP67 on protein ligands; 3) To investigate the intracellular location of EBP67 in the secretory pathway and characterize its role in the secretion of tropoelastin; and 4) Determine whether the alpha-v-beta3 integrin plays a role in elastic fiber assembly through its interactions with fibrillin.

在当前的资金期间，我们继续研究EBP67，在产生弹性蛋白的细胞上发现的67 kDa弹性蛋白结合蛋白。与众不同信号传导或粘附受体，EBP67参与了组装弹性纤维通过介导tropoelastin向装配部位的转移在微纤维上。基于许多具有细胞内的常见特征伴侣，我们建议EBP67充当分子伴侣 Tropoelastin。像许多伴侣一样，EBP67优先结合疏水序列已发展为选定释放的机制蛋白质配体，并参与寡聚组件。 EBP67也是如此展示了许多表明它可能在热带分泌的细胞内管理，例如细胞内与tropoelastin以及与细胞骨架成分，可作为移动EBP67-热素的电机复合物。我们还发现，一种61 kDa蛋白可以用 EBP67是TCP-1，本身就是细胞质伴侣的主要组成部分。这 EBP67可能是分泌蛋白的伴侣的可能性是伴侣范式的重要新扩展。在当前资助期间进行的另一个重要观察是整联蛋白α-V-BETA3与微纤维蛋白结合纤维蛋白。这提出了一个有趣的可能性，即alpha-v-beta-3是等离子体上弹性纤维组件位点的组成部分膜。这些装配位点形态上类似于焦点接触以膜的致密区域为特征细胞质侧的细胞骨架元素。考虑到倾向 alpha-v-beta3将焦点接触与焦点接触并与细胞骨架，我们假设该整合蛋白在通过其桥接相互作用来定义装配站点质膜上的细胞内细胞骨架和原纤维蛋白。我们未来的目标是继续表征EBP67及其辅助蛋白并探索EBP67作为分子的可能功能伴侣。我们还将研究alpha-v-beta3整合素的可能作用在弹性纤维组件中。最后，我们希望更好地定义弹性细胞表面上的纤维组件位点。我们的具体目的是：l）进一步表征了EBP67及其附件蛋白； 2）表征 EBP67在蛋白质配体上识别的结构基序； 3）到研究EBP67在分泌途径中的细胞内位置并描述其在Tropoelastin的分泌中的作用；和4）确定α-V-Beta3整合素是否在弹性纤维中起作用通过与原纤维蛋白的相互作用组装。