Burgoyne R D, Norman K M
Brain Res. 1986 Aug 27;381(1):113-20. doi: 10.1016/0006-8993(86)90697-9.
We have examined the question of whether alpha-tubulin is detyrosylated during axonal transport in retinal ganglion cell axons and axons of spinal motor neurons. The degree of tyrosylation of alpha-tubulin was estimated from immunocytochemistry and immunoblotting with two anti-alpha-tubulin monoclonals, one of which (YL1/2) recognizes only the tyrosylated form of alpha-tubulin. In the case of retinal ganglion cells, the axons were depleted of tyrosylated alpha-tubulin both in the retina and proximal region of the optic nerve. Distal regions of the axons, in the optic tract, gave a pattern of staining consistent with a reduction in the total level of alpha-tubulin at the expense of detyrosylated alpha-tubulin. Axons within the L5 ventral root, the sciatic nerve and tibial nerve were consistently unstained by YL1/2 indicating that these axons were depleted in tyrosylated alpha-tubulin in all 3 segments. The results indicate that alpha-tubulin destined for axonal microtubules is detyrosylated close to or in cell bodies and not progressively during its transport. Therefore the segregation of detyrosylated alpha-tubulin to axonal microtubules may occur at their site of assembly.
我们研究了α-微管蛋白在视网膜神经节细胞轴突和脊髓运动神经元轴突的轴突运输过程中是否会去酪氨酸化的问题。通过免疫细胞化学和使用两种抗α-微管蛋白单克隆抗体进行免疫印迹来估计α-微管蛋白的酪氨酸化程度，其中一种（YL-1/2）仅识别α-微管蛋白的酪氨酸化形式。就视网膜神经节细胞而言，视网膜和视神经近端区域的轴突中酪氨酸化的α-微管蛋白减少。在视束中，轴突的远端区域呈现出一种染色模式，表明α-微管蛋白的总水平降低，而去酪氨酸化的α-微管蛋白水平升高。L5腹根、坐骨神经和胫神经内的轴突始终未被YL-1/2染色，表明在这三个节段中这些轴突中的酪氨酸化α-微管蛋白均减少。结果表明，用于轴突微管的α-微管蛋白在靠近细胞体或在细胞体内去酪氨酸化，而不是在运输过程中逐渐去酪氨酸化。因此，去酪氨酸化的α-微管蛋白向轴突微管的分离可能发生在它们的组装部位。
