平滑肌收缩
中文名称
通路描述
平滑肌细胞层存在于身体内许多器官和组织的壁中。平滑肌组织缺乏骨骼肌和心肌特有的横纹带模式。平滑肌受自主神经系统、激素、自分泌/旁分泌介质、局部化学信号以及负荷或长度的变化所触发而收缩。钙离子（Ca2+）内流引发的肌动蛋白 - 肌球蛋白交叉桥结合用于产生力量。两种分别由钙离子内流触发的蛋白质途径都参与收缩，即钙调蛋白驱动激酶途径和钙棘蛋白驱动途径。最近有证据表明，肌动蛋白、肌球蛋白和中间丝可能比过去所怀疑的要更不稳定，这些细胞骨架元素的变化以及锚定这些蛋白质的粘附斑的改变可能有助于收缩循环。平滑肌收缩通常使用与横纹肌相同的滑动丝模型变体，但在平滑肌中，肌动蛋白和肌球蛋白丝锚定在粘附斑和密集小体上，这些结构分布在平滑肌细胞表面。当肌动蛋白和肌球蛋白跨越彼此时，粘附斑被拉向密集小体，从而将细胞挤压成较小的形态。收缩由钙 - 钙棘蛋白结合触发，钙棘蛋白在横纹肌中类似地发挥作用。肌球蛋白轻链的磷酸化也参与有效收缩的启动。
英文描述
Smooth Muscle Contraction Layers of smooth muscle cells can be found in the walls of numerous organs and tissues within the body. Smooth muscle tissue lacks the striated banding pattern characteristic of skeletal and cardiac muscle. Smooth muscle is triggered to contract by the autonomic nervous system, hormones, autocrine/paracrine agents, local chemical signals, and changes in load or length.
Actin:myosin cross bridging is used to develop force with the influx of calcium ions (Ca2+) initiating contraction. Two separate protein pathways, both triggered by calcium influx contribute to contraction, a calmodulin driven kinase pathway, and a caldesmon driven pathway.
Recent evidence suggests that actin, myosin, and intermediate filaments may be far more volatile then previously suspected, and that changes in these cytoskeletal elements along with alterations of the focal adhesions that anchor these proteins may contribute to the contractile cycle.
Contraction in smooth muscle generally uses a variant of the same sliding filament model found in striated muscle, except in smooth muscle the actin and myosin filaments are anchored to focal adhesions, and dense bodies, spread over the surface of the smooth muscle cell. When actin and myosin move across one another focal adhesions are drawn towards dense bodies, effectively squeezing the cell into a smaller conformation. The sliding is triggered by calcium:caldesmon binding, caldesmon acting in an analogous fashion to troponin in striated muscle. Phosphorylation of myosin light chains also is involved in the initiation of an effective contraction.
Actin:myosin cross bridging is used to develop force with the influx of calcium ions (Ca2+) initiating contraction. Two separate protein pathways, both triggered by calcium influx contribute to contraction, a calmodulin driven kinase pathway, and a caldesmon driven pathway.
Recent evidence suggests that actin, myosin, and intermediate filaments may be far more volatile then previously suspected, and that changes in these cytoskeletal elements along with alterations of the focal adhesions that anchor these proteins may contribute to the contractile cycle.
Contraction in smooth muscle generally uses a variant of the same sliding filament model found in striated muscle, except in smooth muscle the actin and myosin filaments are anchored to focal adhesions, and dense bodies, spread over the surface of the smooth muscle cell. When actin and myosin move across one another focal adhesions are drawn towards dense bodies, effectively squeezing the cell into a smaller conformation. The sliding is triggered by calcium:caldesmon binding, caldesmon acting in an analogous fashion to troponin in striated muscle. Phosphorylation of myosin light chains also is involved in the initiation of an effective contraction.
所含基因
44 个基因