MICROTUBULES FROM MAMMALIAN BRAIN - SOME PROPERTIES OF THEIR DEPOLYMERIZATION PRODUCTS AND A PROPOSED MECHANISM OF ASSEMBLY AND DISASSEMBLY
MICROTUBULES FROM MAMMALIAN BRAIN - SOME PROPERTIES OF THEIR DEPOLYMERIZATION PRODUCTS AND A PROPOSED MECHANISM OF ASSEMBLY AND DISASSEMBLY
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DOI：
10.1073/pnas.71.4.1159
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发表时间：
1974-01-01
影响因子：
11.1
通讯作者：
GERHART, JC
中科院分区：
文献类型：
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作者：
KIRSCHNER, MW;WILLIAMS, RC;GERHART, JC
采用沉降分析和电镜对纯化的猪脑微管解聚产物进行了检测。无论是低温解聚还是钙离子解聚，完全解聚混合物均呈现出36S和6S组分的浓度依赖平衡。这些成分在电子显微镜下被识别为螺旋状、环状和小颗粒。琼脂糖柱层析得到两个主要部分，一个主要由36S和一些6S物质组成，一个主要由6S物质组成。后者具有高特异性秋水仙碱结合活性，无聚合倾向。对于前导峰材料，这些性质正好相反。有人提出，微管分子（质量为110,000道尔顿）以两种状态存在，这里称为X和Y，其中X态的分子相当于主要存在于尾部部分的物质，而Y态的分子相当于领先部分的物质。本文讨论了微管分子在微管组装和拆卸中的参与，假设这两种状态都具有纵向和横向结合域，其强度取决于温度和钙离子浓度。
Depolymerization products of purified microtubules from porcine brain were examined by sedimentation analysis and electron microscopy. The complete depolymerization mixture exhibited 36S and 6S components in concentration-dependent equilibrium, whether depolymerization was caused by low temperature or by calcium ion. These components were recognized by electron microscopy as spirals and rings, and small particles. Agarose column chromatography yielded two major fractions, a leading one comprising mostly 36S and some 6S material and a trailing one of solely 6S material. The latter had high specific colchicine-binding activity and no tendency to polymerize. For the leading peak material these properties were the converse. It is proposed that tubulin molecules (of mass 110,000 daltons) exist in two states, here called X and Y, with those of the X-state equivalent to the material found predominantly in the trailing fraction, and those of the Y-state equated with the material in the leading fraction. Participation of tubulin molecules in microtubule assembly and disassembly is discussed, based on the assumption that those of both states have longitudinal and lateral binding domains whose strengths differentially depend upon temperature and calcium-ion concentration.