Westermann S, Plessmann U, Weber K
Max Planck Institute for Biophysical Chemistry, Department of Biochemistry, Am Fassberg 11, 37077, Goettingen, Germany.
FEBS Lett. 1999 Oct 1;459(1):90-4. doi: 10.1016/s0014-5793(99)01227-2.
The minimal sequence requirement of Crithidia tubulin polyglutamylase is already fulfilled by tubulin-related peptides carrying a free alpha-carboxylate on a glutamic acid residue. Since the product of each glutamylation step fulfills the substrate requirements necessary for the next cycle, very long side chains are generated with brain tubulin as a substrate. Up to 70 mol of glutamic acid was incorporated per alphabeta-heterodimer. We speculate that the strict choice of a particular glutamate residue for the formation of the isopeptide bond initiating a novel side chain is made by a tubulin monoglutamylase which requires the entire tubulin as substrate.
携带谷氨酸残基上游离α - 羧基的微管蛋白相关肽已经满足了克氏锥虫微管蛋白多聚谷氨酰胺酶的最低序列要求。由于每个谷氨酰胺化步骤的产物都满足下一个循环所需的底物要求，以脑微管蛋白为底物时会产生非常长的侧链。每个αβ - 异二聚体最多可掺入70摩尔谷氨酸。我们推测，引发新侧链的异肽键形成所特定选择的谷氨酸残基是由一种微管蛋白单谷氨酰胺酶做出的，该酶需要整个微管蛋白作为底物。
