Zheng B J, Graham F L, Prevec L
J Gen Virol. 1999 Jul;80 ( Pt 7):1735-1742. doi: 10.1099/0022-1317-80-7-1735.
The major mRNA species in the E1 region of the genome of bovine adenovirus type 3 (BAV3) have been defined by using a combination of PCR, 5' RACE, Northern analysis and DNA sequencing. Independent transcription initiation sites were identified for each of the E1a, E1b and protein IX (pIX) transcription units, but all mRNA species terminated at the same poly(A) addition site immediately downstream of the pIX open reading frame. Thus, the BAV3 E1 region, which consists of the E1a and E1b genes together with that for pIX, functions as a nested overlapping transcription unit. One major mRNA species encoding the E1a protein was found and two mRNAs encoding E1b species, the smaller of which encodes the E1b 17K protein alone and the larger encodes both 17K and 47K E1b proteins, were identified. One mRNA species encodes pIX. The E1a transcript, encoding the predicted 214 residue E1a protein, has four exons. The smaller E1b mRNA has two exons, the second of which corresponds to the last exon of E1a. No introns were detected in the larger E1b mRNA that encodes both the E1b 17K and 47K proteins nor in the mRNA encoding pIX. The relative times of appearance of the mRNAs from the E1-pIX gene region following infection of bovine cells with BAV3 was determined.
利用聚合酶链反应（PCR）、5' 端快速扩增 cDNA 末端（5' RACE）、Northern 分析和 DNA 测序相结合的方法，确定了牛 3 型腺病毒（BAV3）基因组 E1 区域的主要 mRNA 种类。已确定 E1a、E1b 和 IX 蛋白（pIX）转录单位各自独立的转录起始位点，但所有 mRNA 种类均在 pIX 开放阅读框下游紧邻的同一聚腺苷酸化位点处终止。因此，由 E1a 和 E1b 基因以及 pIX 基因组成的 BAV3 E1 区域，作为一个嵌套的重叠转录单位发挥作用。发现了一种编码 E1a 蛋白的主要 mRNA 种类，并鉴定出两种编码 E1b 蛋白的 mRNA，其中较小的一种单独编码 E1b 17K 蛋白，较大的一种编码 17K 和 47K E1b 蛋白。一种 mRNA 种类编码 pIX。编码预测的 214 个氨基酸残基的 E1a 蛋白的转录本有四个外显子。较小的 E1b mRNA 有两个外显子，其中第二个外显子与 E1a 的最后一个外显子相对应。在编码 E1b 17K 和 47K 蛋白的较大 E1b mRNA 以及编码 pIX 的 mRNA 中均未检测到内含子。测定了用 BAV3 感染牛细胞后 E1 - pIX 基因区域的 mRNA 出现的相对时间。
