Fulton C, Kowit J D
Ann N Y Acad Sci. 1975 Jun 30;253:318-32. doi: 10.1111/j.1749-6632.1975.tb19210.x.
Amebae of Naegleria gruberi differentiate into flagellates when transferred from growth medium to non-nutrient buffer. This differentiation, which requires 48 min at 28 degrees C, is dependent on transcription and translation. Tubulin of the flagellar outer doublets comprises about 0.15% of the protein of flagellate, and only about 1-2% of the total tubulin. An antiserum to flagellar (outer-doublet) tubulin contains antibodies that react selectively with flagellar tubulin. Measurements using this antiserum have shown that 97-98% of the flagellar tubulin antigen appears during differentiation. The appearance of tubulin antigen is sensitive to actinomycin D and cycloheximide. Isotope dilution experiments using [35S]methione demonstrated that at least 70% of the flagellar tubulin is synthesized from amino acids during differentiation. Experiments using both the specific antiserum and isotopes have shown that flagellar tubulin synthesis begins about one-third of the way through differentiation, before any morphological change has occurred. These experiments demonstrate that most, if not all, of the flagellar tubulin is synthesized de novo during differentiation, and that cells selectively use a specific subpopulation of tubulin in assembling the outer doub)lets. The results bring into focus major unsolved questions about the synthesis and assembly of flagellar tubulin.
将格氏耐格里变形虫从生长培养基转移至无营养缓冲液中时，其会分化为鞭毛虫。这种分化在28摄氏度下需要48分钟，且依赖于转录和翻译。鞭毛外部双联体的微管蛋白约占鞭毛虫蛋白质的0.15%，仅占总微管蛋白的约1 - 2%。一种针对鞭毛（外部双联体）微管蛋白的抗血清含有能与鞭毛微管蛋白选择性反应的抗体。使用这种抗血清进行的测量表明，97 - 98%的鞭毛微管蛋白抗原在分化过程中出现。微管蛋白抗原的出现对放线菌素D和环己酰亚胺敏感。使用[35S]甲硫氨酸进行的同位素稀释实验表明，在分化过程中至少70%的鞭毛微管蛋白是由氨基酸合成的。使用特异性抗血清和同位素的实验均表明，鞭毛微管蛋白的合成在分化过程约三分之一的时候开始，此时尚未发生任何形态变化。这些实验证明，在分化过程中，大部分（如果不是全部的话）鞭毛微管蛋白是重新合成的，并且细胞在组装外部双联体时选择性地使用特定的微管蛋白亚群。这些结果凸显了关于鞭毛微管蛋白合成和组装的主要未解决问题。
