Zigmond S H, Furukawa R, Fechheimer M
Department of Biology, University of Pennsylvania, Philadelphia 19104.
J Cell Biol. 1992 Nov;119(3):559-67. doi: 10.1083/jcb.119.3.559.
We have studied the effect of the Dictyostelium discoideum 30,000-D actin-bundling protein on the assembly and disassembly of pyrenyl-labeled actin in vitro. The results indicate that the protein is a potent inhibitor of the rate of actin depolymerization. The inhibition is rapid, dose dependent, and is observed at both ends of the filament. There is little effect of 30-kD protein on the initial rate of elongation from F-actin seeds or on the spontaneous nucleation of actin polymerization. We could detect little or no effect on the critical concentration. The novel feature of these results is that the filament ends are free for assembly but are significantly impaired in disassembly with little change in the critical concentration at steady state. The effects appear to be largely independent of the cross-linking of actin filaments by the 30-kD protein. Actin cross-linking proteins may not only cross-link actin filaments, but may also differentially protect filaments in cells from disassembly and promote the formation of localized filament arrays with enhanced stability.
我们研究了盘基网柄菌30000-D肌动蛋白束集蛋白对体外芘标记肌动蛋白组装和解聚的影响。结果表明，该蛋白是肌动蛋白解聚速率的有效抑制剂。这种抑制作用迅速、呈剂量依赖性，且在肌动蛋白丝的两端均能观察到。30-kD蛋白对F-肌动蛋白种子起始伸长速率或肌动蛋白聚合的自发成核作用几乎没有影响。我们检测到其对临界浓度几乎没有影响。这些结果的新特点是，肌动蛋白丝的末端可用于组装，但解聚能力显著受损，而稳态下的临界浓度变化不大。这些效应似乎在很大程度上与30-kD蛋白对肌动蛋白丝的交联作用无关。肌动蛋白交联蛋白不仅可以交联肌动蛋白丝，还可能在细胞中以不同方式保护肌动蛋白丝不被解聚，并促进形成具有更高稳定性的局部肌动蛋白丝阵列。
