The Role of Transcobalamin II in the Methionine Dependency of Human Lymphocytes 1
The Role of Transcobalamin II in the Methionine Dependency of Human Lymphocytes 1
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转钴胺 II 在人淋巴细胞蛋氨酸依赖性中的作用 1
DOI：
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发表时间：
1988
期刊：
影响因子：
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通讯作者：
J. Begley
中科院分区：
文献类型：
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作者：
C. Hall;R. Chu;J. Begley
当用同型半胱氨酸（Hcy）代替蛋氨酸（Met）培养基时，EB病毒转化的正常人B淋巴细胞（RPMI 6410）和有丝分裂原刺激的人外周血淋巴细胞（PBL）均不能很好地复制。与游离Cbl相比，Cbl与人转钴胺素II （TC II）结合显著增加细胞分裂。尽管如预期的那样，TC II使Cbl进入细胞的能力提高了1000倍，但这并不是TC II效应的基础。通过调节培养基中游离Cbl和TC II-Cbl的浓度，等量的Cbl进入细胞，但TC II的效果持续存在。TC II-Cbl不能在没有Met的情况下恢复来自Hcy中Met合成缺陷儿童的病毒转化淋巴母细胞的细胞分裂。TC II并不是通过增强细胞提取物中依赖氯的蛋氨酸合成酶活性来起作用的，但完整细胞通过依赖氯的过程从Hcy产生蛋氨酸的能力似乎在TC II的作用中起作用。
Abstract Neither normal human B lymphoblasts (RPMI 6410) transformed by the EB virus nor human peripheral blood lymphocytes (PBL) stimulated by a mitogen replicated well when the methionine (Met) of the medium was replaced with homocysteine (Hcy). Cbl bound to human transcobalamin II (TC II) substantially increased cell division over that observed when the Cbl of the medium was in the free form. Although, as expected, the TC II enhanced the cell entry of Cbl 1000-fold, this was not the basis of the TC II effect. Through adjustment of the respective concentrations of free Cbl and TC II-Cbl in the medium, equal amounts of Cbl entered the cell, yet the TC II effect persisted. TC II-Cbl did not restore cell division in the absence of Met by virus-transformed lymphoblasts from a child with defective Met synthesis from Hcy. The TC II did not act by enhanced induction of the Cbl-dependent methionine synthase activity of cell extracts but the ability of intact cells to produce Met from Hcy by the Cbl-dependent process appeared to have a role in the TC II effect.