THIN FILAMENTS AND VERTEBRATE SMOOTH MUSCLE CONTRACTION

调节蛋白通过传递信号来控制肌肉收缩 肌动蛋白-肌球蛋白与三磷酸腺苷相互作用的钙依赖性。在脊椎动物中 横纹肌、调节蛋白(原肌球蛋白和肌钙蛋白)有 令人信服地被证明与含有肌动蛋白的薄 细丝。相比之下，脊椎动物的肌肉显然是 肌球蛋白对其轻链钙依赖性磷酸化的调节 亚基激活肌动球蛋白ATPase和收缩事件。 然而，对于Thin和Thin可能共存的可能性存在争议 脊椎动物肌肉中细丝连接的钙调节。到目前为止， 几种可能的细丝连接调节蛋白已经被 在许多实验室中分离出来，但尚未得到证实 是完整的“天然”细丝的组成部分。我们将报道关于 从含有天然细丝的平滑肌中分离出这种天然细丝 除了肌动蛋白和原肌球蛋白，钙调蛋白可能是一种细丝连接的 调节蛋白。Caldesmon是一种主要的钙调蛋白结合蛋白 在平滑肌和非肌肉细胞中。众所周知，它会影响 肌动球蛋白ATPase，并引起F-肌动蛋白聚集。我们的目标是评估 Caldesmon函数及其作为细胞外基质成分的可能调节作用 天然细丝。在这些研究中，我们将测试它对 使用已建立的ATPase分析技术研究肌动蛋白-肌球蛋白的相互作用。我们 还将尝试确定钙离子通道阻滞剂对紧张的影响 使用带皮纤维的开发和维护。此外，我们还将尝试 使用Caldesmon AS的特异性抗体逆转Caldesmon效应 抑制剂。我们还将本地化并确定可能的周期性 天然细丝染色在平滑肌中的钙调蛋白 抗钙调蛋白抗体及其免疫电子显微镜的应用 技巧。肌球蛋白和细丝的双重调节 可能参与收缩反应的微调，以及 这种调制的干扰可能有助于这种 疾病的过程如高血压和哮喘。双重监管也可能是 与“闩锁”过程有关，从而使肌肉张力 以低能源成本进行维护。

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.