Maccioni R B, Seeds N W
Mol Cell Biochem. 1986 Feb;69(2):161-8. doi: 10.1007/BF00224763.
During mouse brain maturation cellular transglutaminase specific activity increases 2.5 fold from day 3 to adulthood. A more pronounced increase is seen during morphological differentiation of mouse neuroblastoma cells, where serum withdrawal induces neurite outgrowth concomitant with a 10 fold increase in transglutaminase specific activity. In contrast, non-dividing neuroblastoma cells lacking neurites show only a 1.5 fold increase in enzyme specific activity. Transglutaminase activity does not reach maximal levels until extensive neurite formation has occurred. More than 80% of the transglutaminase activity is found in the soluble component of brain and neuroblastoma homogenates. Using [3H]-putrescine as the acyl acceptor, endogenous acyl donor substrates in the neuroblastoma cells included proteins that comigrated on SDS-PAGE with tubulin and actin; however, very high molecular weight crosslinked material is the major reaction product in vitro. When purified brain tubulin, microtubule associated proteins and microtubules were compared as exogenous substrates, only the polymeric microtubules were a good acyl donor substrate. Furthermore, preincubation of purified tubulin with transglutaminase and putrescine stimulated both the rate and extent of microtubule assembly. These findings suggest that transglutaminase may mediate covalent crosslinking of microtubules to other cellular components, or the post-translational modification of tubulin by the formation of gamma-glutamylamines.
在小鼠脑成熟过程中，细胞转谷氨酰胺酶的比活性从第3天到成年期增加了2.5倍。在小鼠神经母细胞瘤细胞的形态分化过程中观察到更显著的增加，血清去除诱导神经突生长，同时转谷氨酰胺酶比活性增加10倍。相比之下，缺乏神经突的非分裂神经母细胞瘤细胞的酶比活性仅增加1.5倍。直到广泛的神经突形成发生，转谷氨酰胺酶活性才达到最高水平。超过80%的转谷氨酰胺酶活性存在于脑和神经母细胞瘤匀浆的可溶性组分中。以[3H]-腐胺作为酰基受体，神经母细胞瘤细胞中的内源性酰基供体底物包括在SDS-PAGE上与微管蛋白和肌动蛋白共迁移的蛋白质；然而，非常高分子量的交联物质是体外的主要反应产物。当将纯化的脑微管蛋白、微管相关蛋白和微管作为外源底物进行比较时，只有聚合微管是良好的酰基供体底物。此外，将纯化的微管蛋白与转谷氨酰胺酶和腐胺预孵育可刺激微管组装的速率和程度。这些发现表明，转谷氨酰胺酶可能介导微管与其他细胞成分的共价交联，或通过形成γ-谷氨酰胺对微管蛋白进行翻译后修饰。
