Beltramo D M, Arce C A, Barra H S
Centro de Investigaciones en Quimíca Biológica de Córdoba (CIQUIBIC), UNC-CONICET. Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
Mol Cell Biochem. 1989 Aug 15;89(1):47-56. doi: 10.1007/BF00228279.
Chicken erythroid cells at different stages of maturation were incubated with [14C]tyrosine to analyze the incorporation of this amino acid into the COOH-terminus of alpha-tubulin. The incorporated radioactivity was determined in the microtubule and nonassembled tubulin pools. At all maturation stages, nonassembled tubulin was more labeled than microtubules. Microtubules were significantly labeled in proerythroblasts, labeled to a lesser extent in erythroblasts and not labeled at all in mature erythrocytes. We also studied the distribution of the tyrosinating and detyrosinating enzymes, tubulin:tyrosine ligase and tubulin carboxypeptidase, respectively, between the assembled and nonassembled tubulin fractions. Tubulin:tyrosine ligase behaved as a soluble entity at all maturation stages, whereas tubulin carboxypeptidase was found partially associated with microtubules in chicken proerythroblasts and completely soluble in mature erythrocytes. The marginal band of toad erythrocytes was examined by immunofluorescence using antibodies specific to tyrosinated and to detyrosinated tubulin. This marginal band which is mainly tyrosinated could be detyrosinated by exposure of these cells, previously permeabilized, to exogenously supplied tubulin carboxypeptidase. Toad erythrocytes contained soluble tubulin carboxypeptidase which showed an activity similar to that of chicken erythrocytes.
将处于不同成熟阶段的鸡红细胞与[14C]酪氨酸一起孵育，以分析该氨基酸掺入α-微管蛋白羧基末端的情况。在微管和未组装的微管蛋白池中测定掺入的放射性。在所有成熟阶段，未组装的微管蛋白比微管标记更多。原红细胞中的微管有明显标记，红细胞中的标记程度较低，而成熟红细胞中则完全没有标记。我们还研究了酪氨酸化酶和去酪氨酸化酶（分别为微管蛋白：酪氨酸连接酶和微管蛋白羧肽酶）在组装和未组装的微管蛋白组分之间的分布。微管蛋白：酪氨酸连接酶在所有成熟阶段都表现为可溶性实体，而微管蛋白羧肽酶在鸡原红细胞中部分与微管相关，在成熟红细胞中完全可溶。使用针对酪氨酸化和去酪氨酸化微管蛋白的特异性抗体，通过免疫荧光检查蟾蜍红细胞的边缘带。这条主要为酪氨酸化的边缘带，在这些预先通透化的细胞暴露于外源提供的微管蛋白羧肽酶时，可以被去酪氨酸化。蟾蜍红细胞含有可溶性微管蛋白羧肽酶，其活性与鸡红细胞的相似。
