Role of Myosin in Intestinal Brush Border Function

肌球蛋白在肠和结肠上皮细胞刷状边界结构和功能中的作用将被研究。在刷状边缘细胞骨架中，肌凝蛋白与两个结构域有关：一个结构域包括终端网，它交联微绒毛核心肌动蛋白丝束，另一个结构域包括围绕终端网的肌动蛋白丝的收缩环。肌球蛋白的两个子集是不同的提取从刷边界：一个是参与终端网收缩和一个不是。本研究的目的是确定这两个亚群的分子基础。在刷状边界表达肌球蛋白同工酶的可能性，以及肌球蛋白同工酶与肌球蛋白亚群之间的关系将被研究。肌凝蛋白的每一个子集相对于终端网络的两个主要结构域的定位也将被确定。在胚胎发育过程中，肌球蛋白同工酶的表达和亚群定位与肠道发育的正常顺序有关。最后，一个肌凝蛋白亚群的稳定结构关联表明，它可能与细胞骨架中的多个肌动蛋白相互作用。在刷状边缘结合肌球蛋白的蛋白质将被识别和定位。这项研究的结果可能表明，肌凝蛋白在刷状边界功能中发挥不止一种作用，并且特定的肌凝蛋白在单个细胞骨架系统中发挥特定的功能。这为细胞骨架蛋白经常由多基因家族编码的一般观察增加了新的意义。

The role of myosin in the structure and function of brush borders isolated from intestinal and colonic epithelial cells will be investigated. In the brush border cytoskeleton, myosin is associated with two structural domains: one comprising the terminal web where it crosslinks the microvillus core bundles of actin filaments, and the other a contractile ring of actin filaments that surrounds the terminal web. Two subsets of myosin are differentially extractable from the brush border: one that is involved in terminal web contraction and one that is not. The aim of this research is to determine the molecular basis for the two subsets. The possiblity that more than one isozyme of myosin is expressed in the brush border, and the relationship between myosin isozymes and the subsets of myosin will be investigated. The localization of each of the subsets of myosin with respect to the two major structural domains of the terminal web will also be determined. Because the circumferential ring is organized long before the interroolet region during embryogenesis, the findings on myosin isozyme expression and subset localization will be related to the normal sequence of intestinal development. Finally, the stable structural association of one myosin subset indicates the likelihood that it interacts with more than actin in the cytoskeleton. Proteins that bind myosin in the brush border will be identified and localized. The results of this research may indicate that myosin plays more than one role in brush border function and that a specific myosin performs a specific function within a single cytoskeletal system. This adds new significance to the general observation that cytoskeletal proteins are frequently encoded by multigene families.