Green M, Loewenstein P M
Institute for Molecular Virology, St. Louis University School of Medicine, Missouri 63110.
Cell. 1987 Dec 4;51(5):795-802. doi: 10.1016/0092-8674(87)90102-4.
Bovine papillomavirus type 1 contains the smallest known oncogene (ORF E5), encoding a hydrophobic 44 amino acid protein. To study the biochemical functions of the E5 oncoprotein, we have chemically synthesized it and several deletion mutant peptides. We demonstrate induction of cellular DNA synthesis in growth-arrested cells by microinjection of E5 oncoprotein. This activity can be broken down into two functionally distinguishable domains. Remarkably, the first domain, which alone is sufficient to induce cellular DNA synthesis, contains only the C-terminal 13 amino acids. This is the smallest known protein fragment that can autonomously activate cellular DNA synthesis. The second domain is the hydrophobic middle region, which by itself fails to induce cellular DNA synthesis but confers a 1000-fold increase in specific activity. The N-terminal one-third of the molecule is dispensable for induction of DNA synthesis.
1型牛乳头瘤病毒含有已知最小的癌基因（开放阅读框E5），编码一种由44个氨基酸组成的疏水蛋白。为了研究E5癌蛋白的生化功能，我们已对其及几种缺失突变肽进行了化学合成。我们通过显微注射E5癌蛋白证明了在生长停滞细胞中可诱导细胞DNA合成。这种活性可分为两个功能上可区分的结构域。值得注意的是，单独就足以诱导细胞DNA合成的第一个结构域仅包含C末端的13个氨基酸。这是已知能够自主激活细胞DNA合成的最小蛋白质片段。第二个结构域是疏水的中间区域，其本身不能诱导细胞DNA合成，但能使比活性增加1000倍。分子的N末端三分之一对于DNA合成的诱导是可有可无的。
