Spector E B, Hershfield M S, Seegmiller J E
Somatic Cell Genet. 1978 May;4(3):253-64. doi: 10.1007/BF01542842.
Clonal lines, with either partial or total deficiency of adenine phosphoribosyltransferase (APRT) were derived from the WI-L2 long-term human lymphocyte line by selection for resistance to the adenine analogs 8-azaadenine or 2,6-diaminopurine. Resistance to 8-azaadenine also conferred resistance to 2,6 diaminopurine and vice versa. Cells with 30--40% of wild-type APRT activity were selected by resistance to 0.01 mM 2,6-diaminopurine or 1.40 mM 8-azaadenine. The APRT in the 8-azaadinine-resistant cells exhibited a four- to sevenfold increase in the apparent Km for adenine. Activities of three other purine reutilization and interconversion enzymes in the resistant cells, including hypoxanthine phosphoribosyltransferase (HPRT), adenosine kinase, and adenosine deaminase, were within the range of wild-type activities. The doubling times of the APRT-deficient cells in purine-free medium was not different from wild-type cells. The APRT in the 8-azaadenine-resistant cells did not have an altered mobility in glycerol gradients as compared to wild-type cells. The rate of purine synthesis de novo and intracellular levels of 5-phosphoribosyl-1-pyrophosphate were unchanged in the APRT-deficient cells as compared to WI-L2. The ability of the cells to reutilize exogenous adenine, however, was severely impaired.
通过选择对腺嘌呤类似物8-氮杂腺嘌呤或2,6-二氨基嘌呤具有抗性，从WI-L2长期人类淋巴细胞系中获得了腺嘌呤磷酸核糖转移酶（APRT）部分或完全缺乏的克隆系。对8-氮杂腺嘌呤的抗性也赋予了对2,6-二氨基嘌呤的抗性，反之亦然。通过对0.01 mM 2,6-二氨基嘌呤或1.40 mM 8-氮杂腺嘌呤的抗性选择，获得了具有30%-40%野生型APRT活性的细胞。8-氮杂腺嘌呤抗性细胞中的APRT对腺嘌呤的表观Km增加了4至7倍。抗性细胞中其他三种嘌呤再利用和相互转化酶的活性，包括次黄嘌呤磷酸核糖转移酶（HPRT）、腺苷激酶和腺苷脱氨酶，都在野生型活性范围内。APRT缺陷细胞在无嘌呤培养基中的倍增时间与野生型细胞没有差异。与野生型细胞相比，8-氮杂腺嘌呤抗性细胞中的APRT在甘油梯度中的迁移率没有改变。与WI-L2相比，APRT缺陷细胞中嘌呤从头合成的速率和5-磷酸核糖-1-焦磷酸的细胞内水平没有变化。然而，细胞重新利用外源性腺嘌呤的能力严重受损。
