THIN FILAMENTS AND VERTEBRATE SMOOTH MUSCLE CONTRACTION

调节蛋白通过赋予肌肉收缩 肌动蛋白-肌球蛋白与ATP相互作用的钙依赖性。 在脊椎动物 横纹肌，调节蛋白（原肌球蛋白和肌钙蛋白）， 令人信服地被证明与含肌动蛋白的瘦蛋白有关， 细丝。 相比之下，脊椎动物的平滑肌，显然， 肌球蛋白调节，从而其轻链的Ca 2+依赖性磷酸化 亚基激活肌动球蛋白ATP酶和收缩事件。 然而，关于薄的可能共存存在争议。 脊椎动物平滑肌中与钙离子相关的钙调节。 到目前为止， 已经研究了几种可能的薄的顺磁性连接的调节蛋白， 在一些实验室中分离出来，但它们还没有被证明 是完整的“天然”细丝的组成部分。 我们将报告 从平滑肌中分离这种天然细丝 除了肌动蛋白和原肌球蛋白，钙调蛋白，一个可能的薄的顺磁性连接， 调节蛋白 钙调素是一种主要的钙调素结合蛋白， 在平滑肌和非肌肉细胞中。 众所周知， 肌动球蛋白ATP酶和引起F-肌动蛋白聚集。 我们的目标是评估 钙调蛋白的功能及其作为细胞因子的组成部分可能的调节作用 天然细丝 在这些研究中，我们将测试其对 肌动蛋白-肌球蛋白的相互作用，使用已建立的ATP酶测定技术。 我们 还将试图确定caldesmon对紧张局势的影响 使用结皮纤维进行开发和维护。 此外，我们将尝试 为了逆转钙调素效应，使用钙调素的特异性抗体， 抑制剂的 我们还将定位和确定可能的周期性 平滑肌中钙调蛋白，用 抗钙调素抗体和利用免疫电镜 技术. 平滑肌肌球蛋白和细丝的双重调节 可能参与收缩反应的微调， 这种调制的干扰可能有助于这种 疾病过程如高血压和哮喘。 双重监管也可能是 与“闩锁”过程相关，由此平滑肌张力是 保持低能耗。

Regulatory proteins control muscular contraction by conferring Ca2+-dependence on actin-myosin interactions with ATP. In vertebrate striated muscle, regulatory proteins (tropomyosin and troponin) have convincingly been shown to be linked to the actin-containing thin filaments. In contrast, vertebrate smooth muscle is, apparently, myosin-regulated whereby Ca2+-dependent phosphorylation of its light-chain subunits activates the actomyosin ATPase and the contractile event. Controversy exists, however, on the possible coexistence of thin filament-linked Ca2+-regulation in vertebrate smooth muscle. To date, several possible thin filament-linked regulatory proteins have been isolated in a number of laboratories, but they have not been demonstrated to be components of intact "native" thin filaments. We will report on the isolation of such native thin filaments from smooth muscle which contain besides actin and tropomyosin, caldesmon, a possible thin filament-linked regulatory protein. Caldesmon is a major calmodulin-binding protein found in smooth muscle and in non-muscle cells. It is known to influence actomyosin ATPase and to cause F-actin aggregation. We aim to assess caldesmon function and its possible modulating role as a component of the native thin filament. In these studies we will test its influence on actin-myosin interaction using established ATPase assay techniques. We will also attempt to determine the influence of caldesmon on tension development and maintenance using skinned fibers. Additionally we will try to reverse caldesmon effects using specific antibodies to caldesmon as inhibitors. We will also localize and determine possible periodicity of caldesmon in smooth muscle by staining native thin filaments with anti-caldesmon anti-bodies and by utilizing immunoelectron microscopic techniques. The dual-regulation of smooth muscle myosin and thin filaments may be involved in the fine-tuning of the contractile response, and disturbances of such modulation may contribute to the development of such disease processes as hypertension and asthma. Dual regulation also may be associated with the "latch" process, whereby smooth muscle tone is maintained at low energy cost.