REGULATION OF ACTIN POLYMERIZATION BY VILLIN, A 95,000 DALTON CYTOSKELETAL COMPONENT OF INTESTINAL BRUSH-BORDERS
REGULATION OF ACTIN POLYMERIZATION BY VILLIN, A 95,000 DALTON CYTOSKELETAL COMPONENT OF INTESTINAL BRUSH-BORDERS
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DOI：
10.1016/0092-8674(80)90550-4
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发表时间：
1980-01-01
期刊：
影响因子：
64.5
通讯作者：
POWELL, LD
中科院分区：
文献类型：
--
作者：
CRAIG, SW;POWELL, LD
从鸡肠上皮细胞的刷状缘细胞骨架中纯化出 95,000 道尔顿的肌动蛋白结合多肽，绒毛蛋白，其同质性达到 98%。在体外，这种蛋白质对肌动蛋白的聚合发挥控制作用。在存在绒毛蛋白的情况下，可检测到的肌动蛋白聚合之前的滞后期缩短，并且稳态平衡粘度与存在的绒毛蛋白的量成比例地降低。绒毛蛋白：肌动蛋白的摩尔比为 1:40 导致奥斯特瓦尔德粘度降低 70%。 1:600的比例即可检测到显着效果。这些比率具有生理相关性，因为刷状缘中的绒毛蛋白：肌动蛋白的比率为 1:13，而孤立的微绒毛中的比率为 1:9-12。粘度的降低反映在蛋白质数量的增加，但在 150,000 倍时未能沉淀。 g 60 分钟。通过抑制 DNAase I 对肌动蛋白单体的不可沉淀蛋白进行的测定表明，绒毛蛋白的存在并未显着改变单体的浓度。对染色阴性、不可沉淀的肌动蛋白进行电镜检查表明，肌动蛋白聚合过程中绒毛蛋白的存在导致产生短寡聚体，这些寡聚体不能相互退火形成长丝。当将 Villin 添加到完全聚合的肌动蛋白样品中时，Villin 还可有效降低 F-肌动蛋白的粘度。绒毛显然是细胞骨架结构的重要体内调节剂，并且暗示着细胞形状和运动性的调节剂。
A 95,000 dalton actin-binding polypeptide, villin, was purified to 98% homogeneity from brush border cytoskeletons of chicken intestinal epithelial cells. In vitro, this protein exerts control over the polymerization of actin. In the presence of villin, the lag phase preceding detectable actin polymerization is shortened and the steady state equilibrium viscosity is reduced in proportion to the amount of villin present. A molar ratio of villin:actin of 1:40 results in a 70% reduction of the Ostwald viscosity. Significant effects can be detected at a ratio of 1:600. These ratios are physiologically relevant because the ratio of villin:actin in brush borders is 1:13 and in isolated microvilli is 1:9-12. Reduction of viscosity is mirrored by an increase in the amount of protein which fails to sediment at 150,000 .times. g for 60 min. An assay of the nonsedimentable protein for actin monomers by the inhibition of DNAase I showed that the concentration of monomer was not significantly altered by the presence of villin. EM examination of negatively stained, nonsedimentable actin demonstrated that the presence of villin during actin polymerization results in the production of short oligomers which cannot anneal with each other to form long filaments. Villin is also effective in reducing the viscosity of F-actin when it is added to a fully polymerized actin sample. Villin is apparently an important in vivo regulator of cytoskeletal structure and, by implication, of cell shape and motility.