CYTOCHALASIN AND PROTEINS THAT AFFECT ENDS OF F-ACTIN

本项目的长期目标是了解 肌动蛋白丝的组装以及丝与 其他细胞结构用于力的产生和传递。 在 近几年来，研究的重点一直是结构， 和张力蛋白的功能，张力蛋白是一种涉及连接 肌动蛋白丝的膜和其他结构，并在信号 转导 这种蛋白质有能力结合到快速- 生长结束（倒刺结束）的肌动蛋白丝在体外，抑制 在那些末端聚合和解聚。 它是唯一的 一种已知在许多蛋白质中发现的具有SH 2结构域的细胞骨架蛋白 参与信号转导，并在酪氨酸磷酸化 用生长因子刺激或转化的细胞中的残基 致癌病毒 免疫荧光实验表明， 蛋白质存在于许多不同类型的位置， 肌动蛋白丝的末端锚定在细胞膜上或其他 结构（例如，肌肉的z线，平滑肌的致密斑块， 心肌闰盘，成纤维细胞粘连斑， 上皮细胞的粘附小带等）。 拟建项目 （a）研究结构 张力蛋白的亚分子结构域参与相互作用 与肌动蛋白、磷脂、信号转导蛋白、蛋白质 激酶、细胞骨架蛋白等，并确定可能的 这些领域之间的相互作用。(b)表征和比较 不同形式的肌肉和非肌肉的结构和功能 张力蛋白的分子克隆和免疫定位， 在平滑肌中丰富的形式，没有明显的肌动蛋白结合活性。 (c)张力蛋白结合组分的鉴定和表征 除了肌动蛋白，使用结合测定、交联 反应，并选择性洗脱，然后掺入标记的 张力进入分离的粘附斑块、z盘等。 张力结构的改变（例如，磷酸化，蛋白水解， 等等）。并将这些修饰与细胞骨架的变化联系起来， 组织对生长因子刺激的反应，肿瘤性的 改造，药物治疗等结果的建议 在这个项目中的研究将增加我们对 与肌肉组织和各种非肌肉组织有关的疾病 细胞

The long term goal of this project is to understand the regulation of the assembly of actin filaments and the attachment of the filaments to other cellular structures for force generation and transmission. In the past several years, the focus of the research has been on the structure and function of tensin, a type of protein implicated in the linkage of actin filaments to membranes and other structures, and in signal transduction. This protein has the capability to bind to the fast- growing ends (barbed ends) of actin filaments in vitro, inhibiting polymerization and depolymerization at those ends. It is the only cytoskeletal protein known to have the SH2 domain found in many proteins involved in signal transduction, and is phosphorylated at tyrosine residues in cells stimulated with growth factor or transformed by oncogenic virus. Immunofluorescence experiments showed that this type of protein is present in many different types of locations where the ends of actin filaments are anchored to the cell membrane or to other structures (e.g., z-lines of muscle, dense plaques of smooth muscle, intercalated discs of cardiac muscle, adhesion plaques of fibroblasts, zonula adherens of epithelial cells etc.). The proposed project is divided into the following components: (a) The study of the structure and function of sub-molecular domains of tensin involved in interaction with actin, phospholipids, signal transduction proteins, protein kinases, cytoskeletal proteins, etc., and to determine the possible interplay among these domains. (b) Characterization and comparison of the structure and function of different forms of muscle and nonmuscle tensin, including molecular cloning and immunolocalization of an abundant form in smooth muscle with no apparent actin binding activity. (c) Identification and characterization of tensin-binding components other than actin with the use of binding assays, cross-linking reactions, and selective elution followed by incorporation of labelled tensin into isolated adhesion plaques, z-discs, etc. (d) Study the modifications in tensin structure (e.g., phosphorylation, proteolysis, etc.) and correlate these modifications to changes in cytoskeletal organization in response to growth factor stimulation, neoplastic transformation, drug treatment, etc. The results of the proposed studies in this project will increase our general understanding of diseases relating to muscle tissue and to various types of nonmuscle cells.