A factor in serum and amniotic fluid is a substrate for the tRNA-modifying enzyme tRNA-guanine transferase.
A factor in serum and amniotic fluid is a substrate for the tRNA-modifying enzyme tRNA-guanine transferase.
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血清和羊水中的一个因子是 tRNA 修饰酶 tRNA-鸟嘌呤转移酶的底物。
DOI：
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发表时间：
1979
影响因子：
11.1
通讯作者：
W. R. FARKASt
中科院分区：
文献类型：
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作者：
Jon R. KATZEt;W. R. FARKASt
Q因子，一种在动物血清中发现的物质，使培养的哺乳动物细胞（L-M）产生含有排队素（“核苷Q”的碱基，排队素）的tRNA，已从牛羊水中纯化到均质性。Q因子在无血清培养基培养的L-M细胞中引起含Q tRNAAsp的出现，并以此作为监测Q因子纯化的实验。Q因子是兔网状细胞trna -鸟嘌呤转移酶的竞争性鸟嘌呤抑制剂，其K1为4.5 × 10(-8) M. Q因子在L-M细胞和trna -鸟嘌呤转移酶试验中均被高碘酸盐或溴化氰灭活，两者均与排队反应。在L-M细胞中，在培养基中加入纯Q因子后24小时内，无Q的tRNAAsp几乎完全转化为含Q的tRNAAsp；放线菌素D、环己亚胺和环亮氨酸分别是RNA合成、蛋白质合成和核酸甲基化的抑制剂，不抑制这种转化。在纯兔网织细胞trna -鸟嘌呤转移酶的催化下，Q因子与兔网织细胞无Q tRNAHis的反应产物在层析上与含Q tRNAHis难以区分。
Q factor, a substance found in animal serum that enables cultured mammalian cells (L-M) to produce tRNA containing queuine (the base of "nucleoside Q", queuosine), has been purified to homogeneity from bovine amniotic fluid. Q factor causes the appearance of Q-containing tRNAAsp in the L-M cells cultivated in serum-free medium, and this was used as an assay to monitor the purification of Q factor. Q factor is a competitive inhibitor of guanine for rabbit reticulocyte tRNA-guanine trnsferase, with a K1 of 4.5 x 10(-8) M. Q factor is inactivated in both the L-M cell and tRNA-guanine transferase assays by treatment with periodate or cyanogen bromide, both of which react with queuine. In L-M cells, nearly complete conversion of Q-free to Q-containing tRNAAsp is observed within 24 hr after addition of pure Q factor to the medium; actinomycin D, cycloheximide, and cycloleucine, inhibitors of RNA synthesis, protein synthesis, and nucleic acid methylation, respectively, do not inhibit this conversion. The product of the reaction, catalyzed by pure rabbit reticulocyte tRNA-guanine transferase, between Q factor and rabbit reticulocyte Q-free tRNAHis is chromatographyically indistinguishable from Q-containing tRNAHis.