Nevins J R, Ginsberg H S, Blanchard J M, Wilson M C, Darnell J E
J Virol. 1979 Dec;32(3):727-33. doi: 10.1128/JVI.32.3.727-733.1979.
The time course of appearance of transcriptional activity from five early adenovirus type 2 transcription units has been determined. RNA complementary to region 1A (1-4.4 map units), the first region to be transcribed, was detectable at 45 min after infection; a maximal rate of RNA synthesis was reached at 3 h after infection and was maintained thereafter for at least 6 h. RNA from region 2 (75-56 map units), which encodes the mRNA for the 72,000-dalton DNA-binding protein, was the last to be synthesized; transcription commenced at about 2 h postinfection, reached a maximum at 7 h, and then declined. Transcription of regions 3 (76-86 map units) and 4 (99-91 map units) reached a maximal value at 3 h postinfection. The rates of RNA synthesis from these regions then declined over the next 6 h. The decline of transcription from regions 2 and 4 appeared to be a specific repression of these transcription units. The repression did not occur in the absence of protein synthesis, suggesting that a viral protein might be involved. Transcription of all early regions was initiated and continued for at least 2 to 3 h in cells that were treated with cycloheximide or emetine before and during infection, suggesting that at least the initiation of RNA synthesis from the five early adenovirus type 2 transcription units does not depend on the formation of a viral protein. Moreover, mRNA was formed in the absence of protein synthesis that hybridized to DNA fragments representing each of the five early transcription units. The increase in mRNA accumulation in the presence of cycloheximide (or emetine) does not appear to be due to increased RNA synthesis; thus, either increased mRNA stability or increased efficiency of nuclear RNA processing must occur.
已确定了来自五个早期2型腺病毒转录单位的转录活性出现的时间进程。与1A区（1 - 4.4图谱单位）互补的RNA，即第一个被转录的区域，在感染后45分钟即可检测到；RNA合成的最大速率在感染后3小时达到，并在此后至少维持6小时。来自2区（75 - 56图谱单位）的RNA，其编码72,000道尔顿DNA结合蛋白的mRNA，是最后合成的；转录在感染后约2小时开始，在7小时达到最大值，然后下降。3区（76 - 86图谱单位）和4区（99 - 91图谱单位）的转录在感染后3小时达到最大值。这些区域的RNA合成速率随后在接下来的6小时内下降。2区和4区转录的下降似乎是这些转录单位的特异性抑制。在没有蛋白质合成的情况下不会发生这种抑制，这表明可能涉及一种病毒蛋白。在感染前和感染期间用环己酰亚胺或依米丁处理的细胞中，所有早期区域的转录都起始并持续至少2至3小时，这表明至少从五个早期2型腺病毒转录单位开始的RNA合成不依赖于病毒蛋白的形成。此外，在没有蛋白质合成的情况下形成了与代表五个早期转录单位中每一个的DNA片段杂交的mRNA。在存在环己酰亚胺（或依米丁）的情况下mRNA积累的增加似乎不是由于RNA合成增加；因此，必然发生了mRNA稳定性增加或核RNA加工效率提高的情况。
