Palmer K A, De Giovanni-Donnelly R
Toxicol Ind Health. 1985 Nov;1(3):1-12. doi: 10.1177/074823378500100301.
Thymidine kinase (TK) was isolated from four different cell lines (TK +/+ P4, TK +/- P4.3.4, TK +/- 3.7.2C, and TK -/- P4.3) that represent the genotypes of L5178Y mouse lymphoma cells. TK isolated from each of the different cell lines was characterized with respect to the estimated isoelectric point (pI), temperature sensitivity, estimated substrate dissociation constants (Km), estimated inhibitor constant (Ki), and response to the activator deoxycytidine diphosphate. The characteristics of TK from the different cell lines were compared to determine whether the product of the TK gene was changed by the mutation that produced the TK -/- genotype and reverse mutation to the TK +/- genotype. The results indicate that the TK enzymes isolated from the TK +/+ P4, TK +/- P4.3.4, and TK +/- 3.7.2C cells have similar, if not the same, characteristics. The small amounts of TK associated with TK -/- P4.3 and the mitochondria from TK +/+ P4 had similar characteristics, and both were different in many respects from the TK associated with the TK +/+ P4, TK +/- P4.3.4, and TK +/- 3.7.2C. These results raise a question about whether a structural gene is the target for chemical mutagens in the L5178Y TK +/- assay; however, this can only be answered by the isolation of the TK gene from each of the L5178Y genotypes and determination of the nucleotide sequence.
胸苷激酶（TK）是从代表L5178Y小鼠淋巴瘤细胞基因型的四种不同细胞系（TK +/+ P4、TK +/- P4.3.4、TK +/- 3.7.2C和TK -/- P4.3）中分离出来的。从每个不同细胞系中分离出的TK，针对估计的等电点（pI）、温度敏感性、估计的底物解离常数（Km）、估计的抑制剂常数（Ki）以及对激活剂二磷酸脱氧胞苷的反应进行了表征。比较了来自不同细胞系的TK的特性，以确定TK基因突变产生TK -/- 基因型以及回复突变为TK +/- 基因型后，TK基因的产物是否发生了变化。结果表明，从TK +/+ P4、TK +/- P4.3.4和TK +/- 3.7.2C细胞中分离出的TK酶具有相似（即便不完全相同）的特性。与TK -/- P4.3相关的少量TK以及来自TK +/+ P4的线粒体具有相似的特性，并且在许多方面都与与TK +/+ P4、TK +/- P4.3.4和TK +/- 3.7.2C相关的TK不同。这些结果引发了一个问题，即在L5178Y TK +/- 检测中，结构基因是否是化学诱变剂的作用靶点；然而，这只能通过从每种L5178Y基因型中分离出TK基因并确定核苷酸序列来回答。
