Mooseker M S, Coleman T R
Department of Biology, Yale University, New Haven, Connecticut 06511.
J Cell Biol. 1989 Jun;108(6):2395-400. doi: 10.1083/jcb.108.6.2395.
The 110-kD protein-calmodulin complex (110K-CM) of the intestinal brush border serves to laterally tether microvillar actin filaments to the plasma membrane. Results from several laboratories have demonstrated that this complex shares many enzymatic and structural properties with myosin. The mechanochemical potential of purified avian 110K-CM was assessed using the Nitella bead motility assay (Sheetz, M. P., and J. A. Spudich. 1983. Nature (Lond.). 303:31-35). Under low Ca2+ conditions, 110K-CM-coated beads bound to actin cables, but no movement was observed. Using EGTA/calcium buffers (approximately 5-10 microM free Ca2+) movement of 110K-CM-coated beads along actin cables (average rate of approximately 8 nm/s) was observed. The movement was in the same direction as that for beads coated with skeletal muscle myosin. The motile preparations of 110K-CM were shown to be free of detectable contamination by conventional brush border myosin. Based on these and other observations demonstrating the myosin-like properties of 110K-CM, we propose that this complex be named "brush border myosin I."
肠刷状缘的110-kD蛋白质-钙调蛋白复合物（110K-CM）可将微绒毛肌动蛋白丝横向连接至质膜。多个实验室的结果表明，该复合物与肌球蛋白具有许多酶学和结构特性。使用丽藻珠运动分析方法（Sheetz, M. P., and J. A. Spudich. 1983. Nature (Lond.). 303:31 - 35）评估了纯化的禽源110K-CM的机械化学潜能。在低钙条件下，包被有110K-CM的珠子与肌动蛋白束结合，但未观察到运动。使用乙二醇双四乙酸/钙缓冲液（约5 - 10 microM游离钙）时，观察到包被有110K-CM的珠子沿肌动蛋白束移动（平均速率约为8 nm/s）。其移动方向与包被有骨骼肌肌球蛋白的珠子相同。结果显示，110K-CM的运动制剂未被传统的刷状缘肌球蛋白检测到污染。基于这些以及其他证明110K-CM具有类肌球蛋白特性的观察结果，我们建议将该复合物命名为“刷状缘肌球蛋白I”。
