Tashiro T, Komiya Y
Neuroscience. 1983 Aug;9(4):943-50. doi: 10.1016/0306-4522(83)90283-x.
One week after injection of L-[35S]methionine into the dorsal motor nuclei of the guinea-pig, labelled tubulin carried down the vagal nerve by the slow phase of axonal transport was analysed by one- and two-dimensional gel electrophoresis. Transported tubulin showed a much stronger labelling of the beta-subunit. Isoelectric focussing revealed that both alpha- and beta-subunits were composed of several components. Labelled tubulin was isolated from the brain by cycles of polymerisation and depolymerisation after injection of L-[35S]methionine into the lateral ventricle, for comparison with transported tubulin from the vagal nerve. In addition to the two alpha-components and three beta-components detected in both preparations, axonally transported tubulin contained an extra component (TAX) with a molecular weight corresponding to that of beta-tubulin and with the same isoelectric point as alpha-tubulin. The axon-specific component TAX co-polymerised with tubulin isolated from the brain. Upon peptide mapping by limited proteolysis, the peptide pattern generated from TAX was similar to that of the alpha-tubulin. It is concluded that the axonally transported tubulin contains a modified alpha-subunit which is not found in the bulk of brain tubulin.
在豚鼠背运动核注射L-[35S]甲硫氨酸一周后，通过一维及二维凝胶电泳分析了由轴突运输慢相携带沿迷走神经下行的标记微管蛋白。运输的微管蛋白显示β亚基的标记要强得多。等电聚焦显示α和β亚基均由多个成分组成。在向侧脑室注射L-[35S]甲硫氨酸后，通过聚合和解聚循环从脑中分离出标记的微管蛋白，以便与来自迷走神经的运输微管蛋白进行比较。除了在两种制剂中检测到的两个α成分和三个β成分外，轴突运输的微管蛋白还含有一种额外的成分（TAX），其分子量与β微管蛋白相当，等电点与α微管蛋白相同。轴突特异性成分TAX与从脑中分离的微管蛋白共聚。通过有限蛋白酶解进行肽图谱分析时，TAX产生的肽图谱与α微管蛋白的相似。得出的结论是，轴突运输的微管蛋白含有一种修饰的α亚基，而在大部分脑微管蛋白中未发现这种亚基。
