Hutton J J, Wiginton D A
Ann N Y Acad Sci. 1985;451:227-37. doi: 10.1111/j.1749-6632.1985.tb27113.x.
The human adenosine deaminase cDNA has been cloned in a lambda-vector. Contained within a sequence of over 1500 nucleotides is an open reading frame of 1089 nucleotides that encodes the amino acids of ADA. The functional ADA gene contains at least six kilobases and has at least two introns. Using in vitro translation, molecular hybridization to ADA cDNA, and S1 nuclease mapping, ADA mRNA has been characterized in lymphoblast lines from seven different ADA-deficient children. All of the lines contain substantial amounts of RNA, which hybridizes specifically to the ADA cDNA. Four of the cell lines contain translatable mRNAs with small defects such as single base substitutions that are not detectable by S1 mapping. Deficiency of ADA activity in these lines appears secondary to synthesis of structurally altered proteins containing simple amino acid substitutions. Three of the lines contain mRNAs with S1 nuclease detectable defects. Some or all of these defective mRNAs are postulated to result from anomalous RNA processing. In these cases the causes of the ADA deficiency may be more complex than simple amino acid substitutions in the protein and could include small insertions or deletions of amino acids as well as changes in the efficiency of translation of the mRNAs.
人腺苷脱氨酶cDNA已被克隆到一个λ载体中。在超过1500个核苷酸的序列中包含一个1089个核苷酸的开放阅读框，该开放阅读框编码ADA的氨基酸。功能性ADA基因至少包含6千个碱基，并且至少有两个内含子。利用体外翻译、与ADA cDNA的分子杂交以及S1核酸酶图谱分析，对来自7名不同ADA缺陷儿童的淋巴母细胞系中的ADA mRNA进行了表征。所有这些细胞系都含有大量能与ADA cDNA特异性杂交的RNA。其中4个细胞系含有可翻译的mRNA，存在一些小缺陷，如单碱基替换，这些缺陷通过S1图谱分析无法检测到。这些细胞系中ADA活性的缺乏似乎是由于合成了含有简单氨基酸替换的结构改变的蛋白质所致。另外3个细胞系含有可被S1核酸酶检测到缺陷的mRNA。推测这些有缺陷的mRNA中的部分或全部是由异常的RNA加工导致的。在这些情况下，ADA缺乏的原因可能比蛋白质中的简单氨基酸替换更为复杂，可能包括氨基酸的小插入或缺失以及mRNA翻译效率的改变。
